United just came out with a trick backpack. It's got straps on the outside to add your big sweater that didn't fit inside or anything else for that matter. The backside has a padded slot for your laptop and the medium sized travel bag has a wet & dry compartment for those times you go to the beach or ended up sweating like a pig at the park session.
It also has an ipod/CD compartment with hidden cable routing (hard to find) plus a mesh pocket.
RRP 39.99 (British Pound Sterling)