There are in fact a great many sites with circuits & schematics. I'd suggest that rather than search for sites; search for the topic of interest, & I think you will be surprised at the links that result. Be aware however, that much will be several years old, & you will need to check that the circuit has worked & is not merely a "copy posting" or similar.
Depends on what kind of schematics you are looking for. Looking for schematics on existing equipment or schematics on general types of circuits. As peter said- if you are looking for general circuits then be aware, just because it is posted does not mean it works well. As they say - you get what you pay for.
Jake.. There are plenty of websites out there, it all depends on what you are looking for.. Example: I had to fix an amp for a school and needed the schematic.What i did is input the model # and it came right up."Now", I'm not saying is that for everything ( give it a try).... Hope this helps..
Here's one you may find useful: "(DIY Audio and Hi-Fi Schematics)":http://diyaudioprojects.com/Schematics/. And I second what Peter and the Davids said.