Having heard the Bose, the iHome, and a few other speakers not mentioned (Virgin Boomtube EX, Edifier MP300, Eclipse Lulet TD307PA), the best semi-portable sound quality/portability tradeoff I've seen thus far are the Klipsch ProMedia 2.0 speakers. They, frankly, sound AMAZING. The bass is very good for their size and they get extremely loud. For $99 they can't be beat and walk all over the iPod dedicated speakersets (except for the Klipsch iFi but that isn't anywhere near portable). You can find 'em at any CompUSA, give them a listen.

Alternatively, another that sounds quite good and is semi-portable is the Altec Lansing iM7.