[The following is a guest post by my good friend Norman J. Harman of Troll and Flame. Norm is a great enthusiast and promoter of pen and paper gaming, and also happened to be the DM of the first D&D game I ever played. Be sure to check out his blog.]
I'm a bit OCD when it comes to counters, trackers, props and other play aides. I've play tested more than a few. This is what I've learned. DM's and games are different so, as always, YMMV. Misses...
Cribbage board: When I first read about this idea I became overly excited, ran out to FLGS, Great Hall Games, and bought a cribbage board and a multitude of pegs. Pegs to track hit points, spell durations, initiative, everything! In play, the board is long and takes up quite a bit of space. Even more so if you want to hide it behind DM screen. The pegs fall out too easily. They are also hard to manipulate when a few of them are plugged in near each other (such as when tracking hit points). One needs to remember (or label which is hard with the tiny pegs) which peg goes with which thing being tracked. There are no notes / history to refer to later. The coup-de-grace, cribbage board is just not as fast or as easy as scribbling on paper or dry erase board.
Tally Counter: Thought this would be orc's knee for tracking rounds during combat. In reality, not so much. Combats don't last all that long. Even though I kept it in my hand I forgot to whack the tally all the time. It was in my hand, meaning other things notes, NPC cards, dice weren't.
Hits...Dry/Wet Erase-Board Besides the obvious mapping and quick drawing functions a corner of a dry erase board or a dedicated one just for the DM has a great many uses. After years of trying newfangled tools I've found erase boards (or paper) are the fastest, lowest impact (time/DM distraction) method of tracking monster hit points and conditions. Tracking time; Mark off rounds of combat with tick marks, note when spell or effect will end. Generic note taker/reminder, e.g. "Door left open/if trap triggered, flood entire area." Note: Prices vary tremendously, shop around. I found large 23"x35" magnetic dry erase boards for $20-30 at Target, over $100 other places. Use as is or remove frame and scribe a square grid on it and bam, awesometastic play surface! It's worth getting a magnetic one.
I've had great success with marking "tracks" on a square gridded magnetic dry erase sheet. Combined with Alea Tools magnetic markers. One under mini, one on each track (e.g. hit points and initiative). Kind of depends how fast/loose your system is if this amount of setup/props is worth it. It really speeds up the grittier / more detailed combat systems. For example it rocks for keeping track of Hackmaster Basic's continuous initiative. Since it's dry erase, can mark right on the time track spell/effect durations, etc.
Tokens, Tokens, Everywhere Glass beads, stones, plastic doodads, and other tokens. Kind of mixed results with these. My first token idea was to have a visual representation of the characters' health. Without the verisimilitude destroying role call of "who's down how many hit points". But, without knowing total hit points, a pile of beads representing damage taken didn't help much. The reverse, handing out beads equal to hit points and then removing them as damage taken is better for knowing who's in danger of death but doesn't show how far a character is "down". Also, hit point totals are so high in 3.X (system I DM'd during my "glass beads for everything!" period) that tracking / counting beads was a chore, even when using different beads to represent larger increments, 5hp. The opposite of the "quick glance" to know character's health idea I had. What to track? Hit points: Meh, see above. With a lower hit point system, using piles of beads to track monsters hit points as DM might be manageable. But, with lower hit points systems there's less to track. [hmmmm, a reason I'm attracted towards the "smaller" systems, ya think?]. Spell/Effect durations: The spell "Greater Awesomeness" lasts 4 rounds. Recipient of spell grabs 4 beads and at start of each round returns one. No more beads, no more awesomeness. But, see Tracking Durations which removes need to track effects. Gold/Treasure: Never tried this myself. Would want different tokens for different denominations. But, gold comes in too large amounts and tracking it from minute to minute is not so important/has no great fun or game impact. Mana/Spell/Psionics points: Again, never used this [haven't used a spell point system recently. But, when I do I'll totally drag out the tokens!] This is one application were tokens would really shine. Verily, if the system is one where points are regained and spent frequently. A reason people moan when "magic point" systems are mentioned is that tracking points is a pain. In conclusion. It's neat to have a tactile whatsit for players to hold and relate to. OTOH, tokens are a bit fiddly and get lost amongst the typical game table's detritus. I suggest picking one or at most two things to track with tokens. When used for everything it is just too confusing what token means what and game devolves into one of token wrangling. If the thing being tracked requires more than a couple tokens supplying each player with a small dish, jar, or some such container to hold their tokens helps managing them. I used empty jars of delicious mustard. All In
Poker chips worked great for awarding XP during game (which mattered cause XP could be spent on things like re-rolls, and plot modifications (btw, that idea was fail. Players are loath to spend XP)). Poker chips could be used for anything tokens are used for with the benefit that denominations are printed on each chip. Every western RPG should be using, some how, poker chips (and some sort of Poker Hand resolution mechanic).
Is It My Turn? 3.x style initiative is complex. The order changes often and unless everyone can easily see their initiative play bogs down. Folded bits of card stock with name of player/"dm monster group" set on top of DM screen is by far the best 3.x initiative tracking system I have ever used. You want the cards to not be too big so they easily fit on screen, half of a 3x5 works well.
Timers, originally an egg timer which I still prefer. They build tension as the players watch the grains slowly run out. These days various phones and handheld devices have timers. 1min & 3min timers is what I have and find most useful. When a player or group is suffering analysis paralysis / stuck in cycle of argument throw down the timer and declare "Decide on an action before the sands run out or fate will decide for you." If it comes to it, what "fate" decides depends on style of DM/campaign and situation. Anything from wandering monster attack, to DM deciding, to player's turn being skipped in combat, to the bad guys get away with the loot. Another good use of timers is when players are making overly "extensive" plans in situations where the characters have only a second or two to think. This builds tension and conveys the dangerous, uncertain atmosphere that poking around ancient crypts should have. Similarly, the thrill of traps, flooding rooms, gas, crushing walls, etc. is magnified when there's a real life time limit until, squish!. Index Card Mania! I'm in love with index cards. They, along with dry erase, are the two most used and useful game aides in my DM arsenal. My biggest problem is wrangling them at the game table. They get mixed up/lost under maps, books and the like.
Get a card holder, or three! For some games a notecard is all that's needed for a character sheet. In others a 3x5 card is handy for significant followers and henchmen. In all games they are perfect for passing "secrets". Such as revealing to the thief what they've found (and for thief to secretly reply what goes "missing" before the party has a look in the treasure chest). Folded into a "tent" with character's name for better verisimilitude at pickup / convention games. Folded into a "tent" and labeled with various conditions (stunned, blind, silenced) they provide very visible reminder to DM and other players (ahem cleric, over here!) I personally find it easy and quick to read over bullet points on a card, put it down, formulate the scene/npc/whatever in my mind and then describe it to players. I use multicolored cards, each color for a different "level" of detail. A stack of these cards and a map is often how I "write" an adventure.
Regional environments; "Silvertown", "Scupi Basin", "Vervigis's Lab". Each has bullet points for the 5 senses, weather, unique things and other notes to help me set the mood of the area. Custom encounter tables on the back. Reused whenever characters are in that area. Scenes and encounters; "Foyer of Misdirection", "Meeting Vervigis", "Gnoll Raid". This will have a few bullet points for description like the regional environment cards. A list creatures(just # and names, stat blocks on their own card) / whatever the scene challenge is. On the back is post encounter loot/reward/aftermath. Conversations; When there might be some big exposition or role-play with NPC's a "conversation card" with notes and probable phrases/questions/answers comes in handy. Rule cards; For instance a card with rules for desert weather/heat effects when you know the party is getting lost in the desert. Clipped to DM screen it is a handy reference. A poor man's customizable screen.
Of course, a DM's craft is never perfected. If you have any suggestions for game aids, any reports of some trick that's worked well, feel free to let me know about it in the comments.