I know this has probably been asked 10,000 times before, but are there any good sites that have sprites, backgrounds, or music that can be used in adventure games (free or not)?
The biggest thing I really need are character sprites
www.spriters-resource.com this site have old games characters sprites, you can re-paint them or just catch them. In my blog (which you can acces here (http://www.jprelease.blogspot.com)) i have a list of usefull tools, that might help you creating sprites or adjusting them. For music, a good think to do is google for SFX and search with a little more depth to get musics. If you need old games musics (Most of the RPG's) send a PM to me and i can send you a great pack with 100+ MIDIS. Hope this help you ;)
When it has been asked thousands of times, why not look at the threads where it *has* been asked (since there should be thousands of them). A simple google image search for "adventure game sprites" will give you a flood of resources- but since most of them will be rips from commercial games, you may want to use them as a template only.
For sprites, check this one.
http://sdb.drshnaps.com/Contact.htm (http://sdb.drshnaps.com/Contact.htm)
Great examples of good shading and suchlike. All ripped though.
For music, there's this...
http://www.mirsoft.info/gamemids.php (http://www.mirsoft.info/gamemids.php)
Depending on what you seek this *could* be heaven ;)
Don't forget InstaGame, maybe a little dated now, but free to use :)
http://www.sylpher.com/ig/