I got the Carradice zipped roll:

http://www.wallbike.com/carradice/zippedroll.html

But I use mine on my handlebars. I like having something I can reach into without pretzeling 180 degrees to reach it, or get off my bike. I eventually want a saddlebag, but will get a larger one that will really hold bunches of stuff. In the meantime since I don't carry a lot with me (I'm just riding in the neighborhood) this is the way the zipped roll looks on the front of the bike:



I could easily stuff a jersey or lightweight jacket or something in it. Or a book or whatever. Right now it carries a couple of basic bike tools, cell phone, iPod, Cliffblox or Lara Bar and on this day, a bank deposit. That pic was made in the drive-through at the bank.