Don't keep that Brendan Benson collection to yourself. Or that Arcade Fire. Heck, even that John Mayer. Plug a set of portable speakers into your iPod, Zune, Zen, or other MP3 player and let the world (or at least the nearby) jam with you. B&H Photo has the JBL On Tour Portable Speaker System for $29.95, plus a reasonable six bucks (ish) for shipping.
These cool-looking curved speakers (which originally sold for $100) run on AC power or a quartet of AAA batteries--the latter good for up to 24 hours of play time, according to JBL. A protective sliding cover doubles as a stand for the speakers, which point the sound upward--arguably the best way to fill a (smallish) room. An included patch cable lets you connect any audio source that has a 3.5mm jack.
CNET had mostly good things to say about the On Tour, while readers were even more effusive, rating it 8.6 out of 10 on average. So take off the headphones and let your tunes fill the air. (No rap, please.)