I reckon the obvious dock picks are the Logitech Pure-Fi Anywhere (the second version of which will be printed in the January issue), which is very compact, stylish and capable for £100, or the B&W Zeppelin if you've got more space and £400 to spare.
The review of the last Logitech is available here - http://whathifi.com/Review/Logitech-Pure-Fi-Anywhere/
While the B&W review is here - http://whathifi.com/Review/BandW-Zeppelin/
Tom Parsons is Staff Writer on What Hi-Fi? Sound and Vision