I replaced the bolts holding the seat in with QR skewers to make seat removal tool-free. The skewers used here are Tranz-X Seatclamp QR 6x30, sometimes listed as 6x3-30.
The nuts that came with the QRs have been drilled out to remove the threads...then turned around to be used as a bushings. (Flange toward the bike)
The bushing is needed to give the QR lever some room away from the fender, allowing a finger to get behind it an pull it out. To tighten: lightly tighten down, then reverse it one turn, clamp it down. Make sure the clamp isn't protruding from under the seat.
If you should happen to order the longer ones (45-60mm), then you will have to shorten and re-thread - make sure there's enough thread left over to drive in to the seat bracket.
Two of these cost me about $15 with shipping back in 2008.
http://www.youtube.com/watch?v=hzGGvHSSJ4wNow I need to find some of these for the tank.