Do you want to know who sampled who ? Who Sampled is the ultimate database of sampled music, remixes and cover songs. It contains over 92000 songs. Each entry shows the original track as well as sampled, so it’s very easy to judge the amount of work required to create such remixed / sampled tune. Sometimes comparing can be very fun but on the other hand it can make some music fans pretty sad.
Very informative website.
More info: WhoSampled.com