Sgtsalt

I'm officially carless as of last month and have been commuting nearly 90 a week on my bike since. I have an over the shoulder bag already, but it is small and ill equipped for what I use it for.

Any recommendations on a nice over the shoulder bag? Keep in mind, I'll be carrying everything from clothing, school books, to groceries in this thing (and who knows what else). I'd like a big bag I suppose, and if it were possible to customize its look myself, that would be a huge plus.

Thanks!
-Salt