It's pretty small, that's for sure. This Iogear WiFi, the GWF001, is as basic as can be. LEDs show signal strenght and access point status and it's thin enough to hang off a keychain without blowing out your pleats. Priced at about $29, it's an easy, if uninformative, way to see if there are open WiFi access points in a 500 foot radius.
IOGEAR Introduces Keychain WiFi Finder [MobileTechReview]