I have an idea for a weekend project. Create a site that allows you to compare size differences between stores.
It is known that clothing sizes between stores differ a lot. A small at H&M could as well be a medium at GAP.
Nowadays, since a lot of people buy clothes online, it would be nice to know which sizes fit you best.
For example. I shop at GAP a lot. I know that I am a medium at GAP. Now, if I wanted to buy something at Forever21 (which I would probably die before I do), I can compare what a medium at GAP is equivalent to at Forever21.