I’ve visited and coveted so much on Mod Cloth. But I am still unable to figure out how to search on items which come in larger sizes. So I’ve tended to avoid the site, instead of being heartbroken. That and I really can’t buy too much. But in the meantime, I have figured out that if you enter “plus-size” in the search, some of the items in both extended sizes and plus sizes will appear. If anyone can figure out how to get to the XLs/16s, let me know. Or maybe you shouldn’t.
Posted too soon! They’ve put up a link in their FAQ: Mod Cloth (additional sizes). Still flawed in the search, but this is dangerous information.