DRUMMER CAFE

You don't want to use a computer I take it?

There are some excellent sample products with human played percussion sequences available.
Stylus RMX would be a no brainer, but there are other sample CD's with world class percussionists doing their 'thang' for you to enjoy playing with.

A do it yourself version would be to add a drum machine that has a decent perc library to your set up. But then you have to program your own grooves.
Sound module-wise, the old EMU Procussion had a vast collection of sounds, which were highly editable. I guess it would be cheap used.
The great thing about Stylus is tempo can be instantly changed without effecting the sounds. You don't have to do too much programming, just choose the grooves. And any sample library based on REX files can be loaded into Stylus.
For example:
http://www.timespace.com/product/ALP-46/6/REX/Afro+Latin+Producer.html
http://www.esoundz.com/details.php?ProductID=1857
http://www.sonicreality.com/viewDetails.php?ProductID=1981

stylus is great but you'll need a DAW to host it.  if you're on mac, soundtrack pro or garageband would work fine-- just load 'em with loops, bounce out your song, and go from there. 

a buddy of mine used to run sequences off his ipod; he'd just plug in a headphone splitter that split the signal to separate mono outs for each channel.  the L channel was just a click, which went to his in-ears; the right channel was the track, which went to the house and monitors.

Most often I use an Intel-based PC.  Windows XP, 4 GB of RAM, ~3000 Mhz processor.