Wifi Watcher

Wifi Watcher is a Yahoo! Widget Engine tool that shows on screen the name and signal strength of the wireless connection network you're currently linked to. It comprises minimal customization options, so even users with limited background in network apps can easily work with this widget.
The interface is based on a circular frame that resembles a gauge, with a red needle pointing out the current WiFi signal strength level. In the center of it you can view the network name.
As far as appearance is concerned, you can change the text color and font name. However, Wifi Watcher does not provide multiple skins for the gauge or any other options, for that matter.
Nevertheless, you can apply the built-in settings provided by the Yahoo! Widget Engine, which are applicable to all supported widgets. It is possible to make the frame stay on top or below all the other windows, ignore mouse events and prevent dragging. Moreover, you can set its opacity level to a preset value, ranging from 20% to 100%.
The widget has a minimal impact on overall performance, since it uses a very low quantity of CPU and RAM. It has a good refresh rate and indicates the WiFi signal strength correctly. Wifi Watcher did not cause the Yahoo! Widget Engine to hang, crash or show error notifications.
The app does not affect user activity, since it's not intrusive. Therefore, you can get a glimpse of the frame while working in other applications without a problem. Unfortunately, the Yahoo! Widget Engine project has been discontinued for a while, so Wifi Watcher shall not be receiving further updates.