Preparing a table for our upcoming report on social finance, we were slogging through website traffic at Compete.com and discovered a startling statistic. In March, traffic to the person-to-person lender Prosper.com was four-fold that of January, growing to more than 1 million unique visitors. That puts it in rarefied company, approximately the same as a top-20 bank such as SunTrust, which according to Compete had just 10% more traffic in March (see chart below).

If those numbers are accurate, and they weren't driven by unsustainable events such as a a mentions in major blogs or media, Prosper may have moved past the early adopter stage, and into the more mainstream web-based financial services arena.

It appears the traffic is converting to registered users. The last time we checked, April 25, the homepage said it had 240,000 registered users. Today, it says 270,000. That's 12% growth in 15 days.