Anyone know of some good sounding portable speakers to use with a mac? Is there such a thing as bluetooth speakers? I'd like to avoid any wires, but I haven't really scouted around for any yet. I really wish Apple somehow wired in better speakers on both my G5 and my al Powerbook.

I use Altec 2121's with my PB, purchased at stores.ebay.com/ELDIRECT quite cheaply (even including shipping). They are wired, but deliver listenable sound (certainly not as good as my regular stereo JBLs, but NOTHING in the world is that good…). There are lots of decent speakers available that just plug right into the computer - I'm partial to Altec (& JBL) from my years doing music & PA sound.

This is a huge thing for some. I haven't really looked into Wireless speakers myself. But, if you want something which is great for "Music" wirelessly the Airport Express is a great way. It's great for listening to Music and other things through your Home Stereo System. iTunes is built with this inside. http://www.apple.com/airportexpress/

Rogue Amoeba actually released an Application called "Airfoil" which allows any audio source from your Mac to be transmitted to the AE. The only thing that is bad about this is there's delay between the transmission. For instance, if you were to try to watch a DVD, the sound would lag.. and it wouldn't be a great experience.

http://www.rogueamoeba.com/airfoil/

When you say portable, I assume you want to avoid power adapters, batteries, etc.

There are USB powered speakers available, anywhere from $20 to $160, that give better sound than PowerBook or iBook built-in speakers.

BlueTooth speakers like these
http://www.abe-hk.com/english/products/bt90s/bt90s.htm
require batteries. USB powered is a better way to go.

Try these:
http://www.alteclansing.com/product_details.asp?pID=XT1