Net seeker

So, I've been thinking about this for a while now: Why isn't there a TRUE WiFi finder dongle thingy (is there? I've never heard of one...) What I'm thinking of us not simply something which senses the existence of a wifi signal, but finds and tests open, unlocked WiFi 'automatically.' Basically, I'm thinking of using a wifi module tied to an 8-bit micro with a push-button and a tri-color LED as a status indicator, running off of whatever necessary battery source (Recharable LiIon via USB?)

It would work something like this:

Push "Search"