GeekTool, in their words “is an application for Mac OS 10.6+. It lets you display various kinds of information on your desktop via 3 default plug-ins.” With a little bit of scripting ability, you can display all sorts of useful information on your desktop.
Here I have some weather, and whatever network interface my MacBook using along with my current IP address. You can download my network interface script here. To get it running, you’ll need to create an IPAddresses.cfg in the same directory you’ve put the script in (I just use Scripts under my home directory). All it contains is a list of the network interfaces to probe, typically just…
…which should be your ethernet and WiFi ports. You can run “ifconfig -a” from the Terminal app if you’re unsure. Once this is done, you can test this in the Terminal app again by running “./IPAddresses.sh” from the directory you stored the script in. You should see an output similar to the screenshot above.
Once this is all working, you just need to drag a new “Shell” widget from GeekTool onto your desktop, and set the Command field to the script location, “/Users/username/Scripts/IPAddresses.sh -c /Users/username/Scripts/” The -c switch just specifies the location of the configuration file you created, the GeekTool scheduler won’t be able to find it otherwise, even if it’s in the same directory. The refresh field is how often you want the script to rerun, I chose 3,600 seconds, but you can go with either shorter or longer intervals. Everything else is pretty much optional, you can select fonts, colours, position, etc. GeekTool will automatically pick black text, so if you have dark backgrounds like I do and you don’t see anything, check the font colour first!