Akai has a huge collection of free samples from various drum machines:

• Akai Kit of the Week samples

They’re mostly vintage drum machine samples, ranging from the Linn Drum to the ubiquitous 808 and 909 to some truly weird ones like the Rhythm Ace and Mattel Synsonic. There are also some non-vintage sounds, mostly generic drums and percussion. The samples are in WAV format within ZIP files. Programs are included for Akai samplers, but the individual samples work fine in the software sampler of your choice.

Via Analogue Industries, who also have a few collections of samples available somewhere, but their site has reorganized and I can’t find them. I’ll update this when I do.

While there are thousands of sample CDs available for purchase in various formats if you need sounds to work with, there’s nothing better than finding a good source of free sounds. One of the earliest I’ve run across is the samples page at Music Machines.

Here you’ll find sounds sampled from vintage drum machines, ranging from classics like the Roland TR-808 and TR-909 to lesser known (and cheesier) units like Casio’s SK-1 and the Univox Micro-Rhythmer-12. There are also some vintage synths like the MiniMoog and Roland Juno.

Most of these are freely usable in your own music, and many can be redistributed. I downloaded a bunch of them several years ago to use in FruityLoops and I end up using them far more than any of the actual drum machines I own.

The rest of the Music Machines site is worth a look too—there are pictures, details, and even schematics for hundreds of vintage machines.