I just use 2 fat quarters, sandwich them with low-loft batting, quilt and sew up the long side. I then add elastic to the top and bottom and add a little loop to hang it. I've given several as gifts the last few months and everyone says "I've always wanted one but never get around to buying or making one". Of course now with using our own bags we probably don't have as many plastic bags, but I still seem to accumulate plenty of them.
I also made my MIL a walker bag. I made one for my sister recently and she really likes it and says she uses it all the time so I thought my MIL might like one too.
I used this tutorial from Quilting According to Annette, but sewed up the pocket to make it 2 pockets, one large enough to put a magazine and then a smaller one, maybe for glasses or something smaller. It's really easy and fast to make.
I made both of these items Sunday afternoon in just a few hours-it's taken me longer to get them wrapped and in the mail!
Edited to add I linked to Crazy Mom Quilts Finish if up Friday