I've never heard them personally, but maybe something like the Anthony Gallo Nucleus Micro speakers. I doubt you get much bass, but they probably sound good and look tiny and easy to pack. Orb makes a similar pair. Never heard those either.
Another way to do it would be to get a small pair of powered (active) speakers, like these Advents: http://www.amazon.com/gp/product/B00005LACB/ref=cm_rdp_product. I had a pair of the predecessor Acoustic Research version of these about 20 years ago when I was a ski bum. They sound pretty good - not audiophile good, but they are cheap, very rugged, and plenty powerful.
A similar option would be these powered JBL's: http://www.bhphotovideo.com/c/product/341563-REG/JBL_LSR6325P_1_LSR6325P_5_25_Biamplified.html