The Not-So-Boring Stuff
I keep coming back to OnyX and using the Logs button. A lot. What Logs does for me is get me to all the logs that Unix keeps about itself automatically. Although the initial dialog box display looks empty, the fun begins when you select a menu.
What you now have available is all the major logs associated with the system. If you select one, it will appear in the white space that is under the popup menus. The maintenance logs (daily, weekly, and monthly) can show you exactly what has happened when you ran those maintenance scripts. (Why use a maintenance script? For example, in Unix OS systems most temporary files have to be explicitly deleted. If not, they just stay there like dead wood and eat up your disk space. You can delete them easily as a batch with a daily maintenance script.)
Console is all the system events that get reported. All these system-level logs are followed in the menu by the logs for the BSD subsystem programs such as Apache, Samba, PPP, and the like. These logs are a great way to see whether the subsystems are having problems.
The Applications popup menu brings up a file selector, with which you can select the report produced from an application. Here's the report produced by an application (SMARTReporter) that checks my hard drive every hour for any predicted failures using the drive's built-in hardware tests.
Pretty simple text output—with just the time and results included. It's also very understandable. Even a machine could parse it.
Let's try another one. The backup utility SuperDuper offers you a choice about which files it won't copy though the use of a simple script editor. If you suspect a file corruption problem is happening on your backup disk, looking at the SD log is the best way to see exactly what did happen during that last file backup, as opposed to what you thought you told it to do.