I'd been looking for ways of making blog buttons for a wee while and the original sites i found didn't seem very intuitive or helpful [or maybe i just needed a bit more help than most folk]
Anyway i found this Brilliant Button Maker.
You can upload images which will automatically resize and the buttons look really great IMO
I've added 3 on the sidebar for my website, my children's illustrators portfolio and for the free e-cards
Its donate ware via paypal