The best places to hunt for schematics are freestompboxes.org and DIYstompboxes.com. But better than that - look for old solid state preamp and amp schematics, some of which can be used as effects.
What I've done in recent years is to learn about the circuits themselves and train myself to use LTSpice, the free circuit simulator from Linear Technologies.
http://www.linear.com/designtools/software/I have created some unique circuits by using LTSpice, some of which I hope to release here. But it's also fun to simulate something like the venerable Tube Screamer and see what tweaking different component values does to the circuit's response!