OpenWiFiSpots - Hotspot location app
Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
Wi-Fi Space - Hotspot location app
Angry IP Scanner - Open-source and cross-platform network scanner designed to be fast and simple to use
pttrns - iPhone and iPad user interface patterns
Advanced IP Scanner - Advanced IP Scanner shows all network devices, gives you access to shared folders, and can even remotely switch computers off. Download it Free.