What are your indispensible "Hand Waving" tools for coming up with stuff on the fly?

[evildmguy]

Everchanging Book of Names

markers and a plexiglas over a grid map.

electronic copies of the map that I can mark or annotate in some way to keep notes.

OneNote - or any note keeping device, down to pen and paper if needed.

Notes of last time and my own campaign notes, which include a good working knowledge of the world and my plans for the NPCs in it. I think about this sort of thing a lot during the week and know what would happen if the PCs never showed up and start changing everything.

Then, I go with the flow and run it based on how things are happening. This might mean making up an encounter or dungeon on the fly, which I am good at with a lot of experience doing as it is the style I prefer or at least have developed over the years.

I admit that I don't know the 4E monsters stats as well as I could but as others have said, I find something close and then use those stats with a little changing to make it fit what they are actually fighting.

I also listen to what the players do and and others suggested, use it if I can. I have to balance it out with what I have already done if I don't think it fits well. Besides, then they don't feel that everything works out exactly as they thought.

A combination of what everyone has said with some other tools to help me improv the situation.

 

[Thasmodious]

I'm right there with evildmguy. I run a mostly improv game and just devote thought to the various elements involved in the campaign and go with the flow. I keep an improv folder handy, specific to the game, along with a pretty standard campaign folder with the usual stuff (NPCs, plots, ideas, encounters, plot points, etc.).

The improv folder has a list of random names to use for NPCs, some random encounter ideas that sound like fun (not random enc. tables, just when I think of a fun encounter, I make some notes on it and see if I can pop it in sometime), some campaign specific random tables, things like that.

For examples, with the random tables, in my 4e game where the PCs run a merc company, I have a couple of tables of random company problems that can crop up during downtimes - a trusted sgt. deciding to break off and start a rival company, the local government imposing new taxes or regulations, a local citizens group opposing to the rowdy mercs, robbery, arson, clients not paying, etc. In my Savage Worlds Firefly game, I have sheets of random troubles for the PC's ship depending on different situations, as well as a stable of interesting and potentially trouble causing random passengers they could take on or random cargoes they could pick up (when those things are not central to the current situation).

Another thing I've been doing lately, and it's somewhat system specific, is working up generic stat sheets for NPCs. I had the idea for 4e a long time ago and do it with SW as well. With 4e, I have two sheets, one lists an average stat line by type (brute, soldier, etc) set at the middle level of the range (5th for heroic, 15th for paragon), and the formula for raising and lowering stats for monsters, along with some of the sample generic groupings from the DMG and some other similar notes. The second page has a number of generic encounter/recharge powers, taken from any number of beasties in the MMs. I can grab stat lines, a couple of powers, flavor them as necessary and have any manner of creature ready to go in a matter of seconds and balanced for the PCs over a 10 level range. This has been indispensable for improv in 4e. I do the same with SW, but it's an easier sheet, generic stat lines for 'citizen', rent a cop/thug, police/pirate, soldier/killer, etc., a section of generic firearm/wpn stats (small pistol, rifle, light melee, hvy melee, etc).