A lot of artist (including your's truly) use samples from other artists and bands in order to get a more lively sound, and of course, because we're just too lazy to program every little note by hand. As audio programming becomes more and more accessible for the masses, sampling equally becomes more popular among young producers as well as it does among big time producers.
In order to keep track of all the samples used in various songs, the guys of WhoSampled created a website where the die hard sample recognisers can live out their passion. Currently tehy feature over 10.000 samples, their origin and where and how they were used. The nifty system shows you who used it and who created it, both ways.
The site is a lot of fun to browse, and you'll be amazed by what you'll find! To get you on-track, here's an example featuring mister Tobin's track "Four Ton Mantis":
Four Ton Mantis:
Uses samples from Aplollo 100's "Mad Mountain King":