Over on his Artworks blog Crabfu has this excellent how-to video on making a touch screen capable stylus from a clutch pencil and conductive foam.
This is one of the best ideas I’ve seen, using a readily available item in the clutch pencil. My thoughts in using it with your mouth are that if you get the right type of clucth pencil it should have a metal push mechanism so contact can be made with the tongue at the top and conducting down to the tip.
As for a more readily everyday available source for conductive foam there’s possibly a golden bit of information in the comments on Crabfu’s post.
“Anonymous said…
Try Scotch Brite sponges – both yellow and blue versions work.”
So remember to look at the comments!
Now for that video:
In addition to a longer mouth stick for desk work, I personally will need something pen length to use while away from desk and with phone on a lanyard around my neck if I’m ever to make the jump to capacitive touch screen phones.
life tools 
I love it! Thank You! I need all the help I can get too, this is genius..
This is a wet system.. Not really practical if you plan to do this on the bus/train or anywhere you might not have access to a cup of water that you can dab your “pen” in..
Technically you could lick the end just about anything, and use that. Sorry.. I don’t want to rain on your efforts, but this is like the 5th I’ve hit that give the wet solution.
I’ve since found these conductive foam solutions are, as you say, wet systems.
Thanks for your comment.