Windows/Mac/Linux: Free application Xirrus Wi-Fi Monitor is a cross-platform Wi-Fi tool that displays available networks on a very cool radar map. More specifically, the app searches for Wi-Fi networks, displays strength, detects rogue access points, and helps you tweak your network for the best signal. The downside: Xirrus Wi-Fi monitor is only available in widget/gadget/desklet form. That means that in order to use it, on XP and OS X you have to install the Yahoo Widget framework, on Linux you have to install the Desklet framework, and on Vista you'll need to re-enable the sidebar gadgets. That's all somewhat of a bummer considering the whole widget craze generally went out the door circa-2006. However, Xirrus remains a worthwhile application with an unquestionably fun execution.