More to explore:
reusable sandwich bags
Anna Can Cook!: reusable ziploc bag
I'm thinking about making this bag.
Tutorial: How to Make Reusable Snack & Sandwich Bags | Green Your Way
for toys, movies, snacks!
Lined drawstring bag
The Ultimate Re-Usable Snack Bag: Machine Washable and Stands Upright. Tutorial. Of all the ones I've seen, this looks like the winner!
American Girl Doll Sleeping Bag Tutorial
Sew These DIY Zipper Bags for Your Summer Outings