Character Options has the license for action figures, and they're really quite nice. A new wave is about to be released, and some of the figures from the first wave are getting hard to find. One place you CAN'T buy Doctor Who toys from is Amazon.co.uk - they can't export them to the US. You can, however, pre-order their exclusive 1st David Tennant season set with the authentic Cyberman head case. Curiously enough, the Cybermen have always been my favorite DW villain, and I have many Cyberman toys, posters and t-shirts collected over the past 30 years. But this new one creeps me out, so I won't be ordering that exclusive boxed set.
I ended up going the eBay route for the first wave figures I wanted. But you can use the links page at the Doctor Who News page at Gallifrey One to start looking:
http://www.gallifreyone.com/links.php
Or the Character Options page - this one links their current Doctor Who line. They aren't the only license holder for Doctor Who, though, just the toys:
http://www.character-online.com/xq/A.../item_list.htm
There is a set of Corgi miniatures that spans the entire Doctor Who series out now, haven't seen miniatures specific to the new series. But there are a number of toys, mugs and such.