I have only recently discovered Shop It to Me (hat tip to Nora over at I bought it, and I loved it). Once you get signed up, you can select from about 500 retailers that you want to follow, as well as the types of clothes you want to return results for and the sizes that you wear. Then, like magic, Shop It to Me polls all your selected retailers' sites for sales on the types of items you're looking for and returns one big page for you to peruse, with big photos. You can narrow the results by type of clothing.
You can even filter by price. The only limitation here is that the price range isn't infinitely customizable. For example, you can set a max of $100 or $50, but nowhere in between, which is unfortunate because I would pay up to $60 for certain items, but no more. Still, it's an incredibly useful resource to check once or twice a week.