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.