I have heard that they send your loan (and credit) information out to 3 or 4 lenders to get you the best possible deal.
One person told me that it dropped his credit score due to all the inquiries in a short period of time. It would be interesting to hear from mortgage brokers that deal with clients trying to use using LendingTree.
I suspect E-loan and other online systems are similar. The website probably takes 1/4% off the top and sends the loan out.
Have you already used it?