1) secret, invitation-only designer sales ala Gilt Groupe and RueLaLa
2) customization ala Shop It To Me
Of course, being the savvy online shopper that I am, I have tried out both trends. Now the examples I listed above are by no means a comprehensive list. I have also tried Top Secret and Ideeli. I think the examples I listed above are the best, most widely used.
Designer sales beginning at 9 am PST/12 noon EST. You got to be ready at 8:59 am to get anything good. These sales are ruthless. In my experience, it's been really hard to get anything in my size. I don't know how it happens, but even at 9:00 am PST, things are already sold out. Still, the merchandise comes in a cool GILT box and everyone at work waits with anticipation to see what you got. I think it's a lot of fun even though it's extremely difficult to get my size.
Same concept as Gilt though I find it easier to shop. Probably less saturated? They will typically have more 'affordable' designers compared to Gilt. Like Free People and Plenty.
Shop It To Me
Customization! Do you wear hard to find sizes? If so, this is the place for you. Basically, you set your customization settings: your sizes, your favorite designers, and/or favorite online shopping sites. SITM then sends you daily emails with sale clothes that fit that description. Makes online shopping easy and less time consuming. They are based out of San Francisco.
Anyways, recommend trying all 3. For invitations to Gilt or RueLaLa, just holla at me. I'll give you the hook up!