Here are a few links to some websites with free samples of all kinds.
Freesound is an open database with samples of every conceivable type: noises, hits, ambients, etc. It is organized by tag, so make sure you search a whole bunch of terms. You can also just browse the highest rated, etc.
This is a blog from the Soundcloud folks that brings together all of the samples that people upload to Souncloud, which is surprisingly a lot. Lots of cool stuff and samples of rarish gear that you can jack and make your own.
This section of the excellent blog Hip Hop is Read is a compilation of drumkits assembled from various hip hop producers. Really good stuff.