+6  A: 

I've used Podsafe Audio in the past for music from independent artists who are perfectly happy for you to use their music in your projects.

Bob Somers
Cool, bookmarked :)
Mecki
+1  A: 

These guys seemed to check out:

PacDV Sounds

John Dunagan
+10  A: 

Freesound provides an excellent, searchable database. It also has a convenient little "player" built in so you can hear the samples before you buy.

The Freesound Project is a collaborative database of Creative Commons licensed sounds. Freesound focusses only on sound, not songs. This is what sets freesound apart from other splendid libraries like ccMixter. New to this site? Read the What is Freesound page to learn more!

Ryan
lol - sure. use it and get sued very likely.
dontWatchMyProfile
A: 

For full songs, you can check Magnatune that has a very artist-friendly business model,

They have a variety of licencing schemes and allow free usage for any non-commercial purpose (including software distributed under an OSI license).

Remo.D
A: 

SoundDogs have a ton of sounds, but it's often hard to find good ones there are so many, and not specifically geared towards applications, but I've used them before. Looking forward to checking out some of the other suggestions here.

chaiguy
Sorry, they're not free though. But the good thing about them is you can purchase individual sounds for $2-$5 each.
chaiguy
that site really doesn't look very "secure".
dontWatchMyProfile