I have the large Banjo Bros. Messenger. Its huge and pretty comfortable. It has a nice wide strap. It's allegedly waterproof.

Here's a review that supports that claim.

http://www.commutebybike.com/2006/12...er-bag-review/

Here's another pretty good review.

http://www.bikecommuters.com/2009/01...messenger-bag/

It's really hard to do better for that price.

My only complaint is that unlike the chrome bags you have to hoist it over your head to put it on. That's a pretty minor complaint for an $80 bag.

Buy it.