http://www.wolfmanluggage.com/
I don't own any, but... I've read a lot of good things about Wolfman Luggage on the ADV site. He's got a whole line of tank bags that aren't magnetic and lots of tail bags too. This is what I plan to try later this year.
So far I've been using a Mountainsmith bag as a tail bag for commuting and it's been great. It's small, so when I'm ready to do some traveling I'll upgrade to some Wolfman bags.
He has good taste in bikes for modeling the bags too.