Not purely cyclocross related but worth a mention is my new small backpack from Brisbane Outdoor Gear. I have been hassling Dave for one of these ever since he mentioned he was working on them. I prefer riding with a backpack as opposed to a messenger bag. I will mainly use this when commuting to work, and seeing as I try to carry as little as possible this bag will be perfect.
The bag has cleverly contoured shoulder straps that feel like they disappear when in a riding position. Inside the bag there are multiple pockets for separating out all your stuff. The standard bag has no padding in the back but the one I got has a custom pocket for adding high density foam. Dave can also add other custom pockets inside the bag as per your requirements.
Check out the BO Gear website for more cycling bags, tool rolls, foot straps and pouches then you will ever wear out.