Unfortunately MacStumbler doesn't work on Intel macs - at least not my Macbook. I needed something to find hotspots whilst I travel so I found (thanks to an earlier user review here) iStumbler. It does just what I want, finds way more hotspots than the standard wifi menu control, tells me at a glance if the hotspot is open, and tells me what services and ports each host supports. Certainly worth the $20 suggested donationware.

Tim