Another addition - there is a tutorial for a pocket with flap here:
http://www.ikatbag.com/2010/11/pocke...ith-flaps.html
If you have a clothing pattern with an appropriately sized pocket piece (would pretty much have to be a kid's shirt, I think) that would work, or you could recycle by using the pocket off of a child's shirt, and save yourself a lot of sewing.