(1) A website that lists the locations of hotspots. See hotspot.
(2) An app in a mobile device or handheld unit that detects the presence of an 802.11 network. Also called a "Wi-Fi detector" or "Wi-Fi signal finder," it reports which hotspots are in the vicinity by network name (SSID) and security type. See hotspot.
A Smartphone Hotspot Finder
Apple coined the phrase "there's an app for that," and there are plenty of smartphone Wi-Fi finder apps like the iPhone app above and all other platforms.
The Handheld Hotspotter
Canary Wireless's Digital Hotspotter identifies more information about hotspots than most apps do: SSID (hotspot name), signal strength, encryption status (Open or Secure) and channel number. This is the SSID of the first found network.