Gilt Groupe "provides access, by invitation only, to Men’s, Women’s and Children’s coveted fashion and luxury brands at prices up to 70% off retail. Each sale lasts 36 hours and features hand selected styles from a single designer."
Woot is "an online store and community that focuses on selling cool stuff cheap. It started as an employee-store slash market-testing type of place for an electronics distributor, but it's taken on a life of its own."
I have not been inside Gilt yet as I need to be invited (hint hint), but I did take a peak at Woot. It has a bit more cluttered feel than blingdaily.com, which is somewhat surprising considering they only sell one product a day as well. This is partly due to their quirky copy on the product. It's also because they have integrated their blog (which is an experience to read in its own right), along with some ads.
But, more importantly, woot.com has two other dedicated "woot" sites they promote - shirt woot and wine woot. I am all over the wine!