Back in the ancient, crazy days of 2002, I bought a graphics tablet for a very reasonable price. It plugged into those newfangled USB port things, and only one of my computers had a USB card installed, but (even on a Mac) I ran it with almost no trouble. The included software worked well, the drivers caused no issues, the plugins for my graphics programs integrated excellently and took full advantage of the tablet's pressure sensitivity, and the hardware was sturdy. I doubt I used it enough to justify the purchase price, but it was an awesome toy and I'm glad I bought it.
Today I dragged the tablet down out of the attic. It has survived two moves and seven years of sloppy handling. It has outlived two computers and seven OS upgrades. I surfed to the manufacturer website, discovered the tablet is still actively supported, downloaded current drivers for OSX, rebooted, and it's performing like it came home from the store yesterday. There's even a handwriting recognition feature that I haven't yet played with.
Ironically, my computer is too old to use my 2002 tablet at full efficiency. My only installation issue is that The GIMP for Mac OS X doesn't have pressure sensitivity support, because the underlying X11 environment for OS 10.4.11 won't recognize the device as a tablet (which they fixed in OS 10.5). With a commercial drawing program, I'd be set.
So, I would like to wholeheartedly endorse Wacom for their breathtaking awesomeness. This sort of computer peripheral product longevity is unheard of, and if you have any use for a drawing tablet whatsoever, they deserve your business.