I've got an Intel Mac Mini for sale, I've had it for about 2 years now, it's been an awesome machine. I ran it as my main machine for awhile, running everything from Photoshop to World of Warcraft on it, and it ran everything without a hitch. I recently upgraded to an iMac and moved this to the home theater, but it was getting used once a month, not nearly enough to justify keeping it. I upgraded the Ram from 512mb to 2gb as soon as I got it, and it's been running like a champ.
It includes all original accessories, and has been formatted with a fresh install of OS X 10.5 Leopard. I left it at the welcome signup screen, so when you turn it on it should throw you right into the signup process.