Wacom are the best, split into two main lines; intuos and graphire. The former are professional ones and the latter are less so, but still good. Trust also do a range but I don't know much about them. I have been after a wacom intuos3 A4 for a while, but I always get outbid

That said, looking at the prices in the US and the excellent exchange rate (for people not in the US) I should be able to get one vastly cheaper in the states than I can here (then get someone to send it over)