LooseTooth
open loop stable
dustin said:SV650. try to find one with some track goodies on it like upgraded suspension...
I'm thinking:
Suzuki SV 650S
Suzuki GS 500F
Kawasaki EX 500
One of the older 600s. A budget would help.
http://www.cycletrader.com/ is your friend. Get somebody who knows what's up to go with you and look at the bike.
Be careful about spelling when you are searching. Whenever I am looking hardcore for a particular model, I will try alternate spellings to get good results. IE, ZX-10R and ZX10R will yield different results