I tried this app a few years back and found it difficult to figure out how to use. I found the need for something like this again, and tried it again. Unfortunately, I didn’t realize I needed a different version for Lion so setting it up wasn’t working (the site wasn’t incredibly clear about that months back: It is the standalone app you need for Lion BTW. The System Prefs Pane does not work). So finally, I tried it yet again, saw the warning, and got it running fairly quickly.
I’ve read the first page of reviews: you don’t _have_ to be a geek to use this app, but it helps. If you know a few Unix shell commands and are willing to learn, you will be well rewarded. Since GeekTool free and anything you leaner can be used in the CLI, you won’t be wasting money or time.
My favorite feature is the ability to make things float over everything else. (I wish it would optionally bring things to the front automatically for a second when updated.)
I already knew all the essential shell commands, so once I got a working version, it was easy to adapt to. (Note: any command that self-updates in place such as “top” will cause problems since GT takes care of refreshing.)
I found just loading the security, system and kernel logs works well, and is light on the processor load (since displaying logs is essentially a tail command: 0.1%CPU {2.53GHz/DC} & ~30MB RAM). Also, I loaded uptime, calendar, and a few other slow refresh commands. It you find that geek tool is taking up too many resources, lower the refresh times.
If you read the sites about configuration, there are a ton of helpful tips, and prebuilt sets one can download. Try DuckDuckGo.com and look for “GeekTool” with “tips” or “configuration” if the developer’s site isn’t enough. (I noticed documentation is getting better on the dev site last time I checked about a month ago.)
BOTTOM LINE: If you want to know what is going on in your system without buying various monitoring programs, want complete configuration, and are willing to read a bit, GeekTool is well worth your time.