The MacAlly BT micro has a dock for charging. It is a really small mouse, though, so may not be appropriate for you.
Actually, the beauty of BT is that there is no usage of USB ports, or anything else attached to your computer. Why not just use a standard cordless mouse if you don't mind tying up a port?
I don't find any problem just replacing batteries in my BT Mighty Mouse, though. I use rechargables, and always have some handy.