Last night I picked up a set of Harman Kardon HK19.5 computer speakers. The speakers I had been using were not amplified, and the maximum volume was... well, very quiet.

They don't get a very good score on Epinions, but I think they're decent. They output 12W per speaker, and that's a lot better than most of the other el-cheapo speakers. And it has a front-mounted headphone jack, which is very handy!