Best portable speakers?

Sound quality is a pretty subjective thing. If 15 people respond with recommendations, you'll probably get 15 completely different answers.

Seems like just about anything is a huge improvment over the internal ones. I have a set of "generic no-name" externals I found at a garage sale for US$2 and they sound great. If we take a car trip, the "garage sale wonders" go with us and the MBP so we can have tunz in the hotel room. However, they are a tad large to pack for airline travel.

I would think that physical size (for portability) might become more of a concern that sound quality. If you buy a three-component system whose tweeters are relatively small like this set-up, you can always decide whether it's worth packing the sub-woofer. Most systems I've seen will work without the sub plugged in.

I should have gone to that garage sale. My traveling external speakers came from a flea market $3.75 negotiated down from $5.

They work great. Like Allen, I use them traveling in the car & staying in hotels for superb music sounds.

I like my Altec Lansing USB Portable Computer Speakers, purchased mid 2006.
Used originally with my iBook but now attached to my MBP.
No doubt the newer versions will be even better.

I also like my Altec Lansing USB speakers. They are small have good sound and come with a hard sided case for travel. I use this whenever I am on the road.