A few months back I checked out what Future Shop, Best Buy, and the Apple Store had to offer, and wound up buying a clearance demo store sample of Apple's own speakers which are unfortunately discontinued. I liked it so much, that I bought a second one, used off of ebay for $125 .... where there's a chance more could be found. To me, it had more bass, and played louder without distortion than all of the dozen or so other offerings I auditioned.
As an added bonus, it runs on batteries as well as the AC cord ( no wallwart involved) that comes with it.
Read about it here:
Awesome iPod Speakers - Apple iPod Hi-Fi - Reviews by PC Magazine
EDIT: I don't know if it's compatible with the latest generation Ipod offerings however.