I've been commuting with a Banjo Brothers Commuter Backpack http://www.banjobrothers.com/products/01150.php. It's made for the bike commuter and works great. This morning I rode into work with my clothes, notebook, computer speakers and the usual tools. It's comfortable and can carry quite a bit. It's worth the $80 that I spent. I've been commuting with my large timbuk2 for a few years. I also tried panniers and other backpacks. This bag is by far the most comfortable with decent sized loads.