Good Mac OSX programs for getting samples/remixing songs?

I am currently wanting to get into remixing songs. I just downloaded Ableton Live 8.0 for my Mac, which I can use to mix/edit/remix songs, but now all I need is a program that I can download a bunch of samples from (various instruments, beats that I could build off of, etc.) Thanks for any ideas or tips.

Remember I’m using a Mac, so no Windows programs por favor.