I just use some old tripods.
They work fine for me, and often turn up cheap at trash & treasure etc.
Stability is not an issue with flash, as long as it doesn't actually fall over. The amount of shake at 1/10000Sec tends to be pretty minimal. Even then, its your light source, not your camera.
To attach most flash heads, you will need a screw to hot shoe adapter
Most camera stores can supply these for not a lot of money. You could also use
http://mpex.com/ItemDetail.aspx?SKUID=6570&SKU=0034447501233&SN=0000&Q=False. They will allow you to add an umbrella to the set-up. You do need to insulate the shoe adapter on these as that part is carved in solid aluminium.
You can also use bungee balls or masking tape to hold your flash in a convenient spot
Also, if you get Nikon SB600/SB800s, they come with a nifty little stand that works on its own, or can be screwed to a tripod. I use them all the time.