I second the Pioneer (+ external case) recommendation. iLife compatible (Apple uses them in towers), speed is as good as everything else, they're reliable, from a solid company, and cheap.
Although you'll probably end up with a 111D--they're newer than the 110D, and a bit better. When Pioneer (or anybody else) comes out with a new model, it pretty much completely replaces the old one, at the same or lower price.
The only thing the Pioneer drives don't offer is Lightscribe, which is fun but the media is expensive anyway, so for me at least not worth it. If you want lightscribe and don't want to bother doing a build-it-yourself, LaCie has nice looking prepackaged externals that, I believe, come with Mac software for lightscribe graphics (is there any alternative software to theirs on the Mac, for that matter?).