I noticed a lot of traffic after the Programmable Web listing. Some of it was directly from there but mostly from stumbleupon.com. Welcome to everyone who discovered SearchMash through that, and thanks to ChaseLightning and DaBug for the recommendation.
I hadn't heard of StumbleUpon before, which probably shows my ignorance, but I'm very impressed by what I've learnt. I've added myself as petewarden, and I'll be having some fun with it. On a business model note, it was very slick that the referring URL in my logs directed me to a customized page asking me if I wanted to create an ad campaign through StumbleUpon. If I was a commercial organization it would be very tempting, since they've already proved they can send traffic to you. From seeing that, I'd bet that SU has a profitable future ahead, and I'm happy for them since they also provide such a neat service for users.