My Mac is dead silent. Even more so after I replaced the already quiet hard drive with a completely silent SSD.
With no audible indication of e.g. swapping/thrashing I was in dire need of some kind of system monitor, capable of at least displaying CPU and memory usage. I wanted the monitor to visible on the desktop all the time but at the same time I’m quite stingy with my screen real estate. This disqualifies CPU monitors implemented as Dashboard Widgets since Widgets are only displayed on the screen when a special key is pressed. It is possible to hack OS X to always display widgets on top of the desktop but widgets steel screen estate. I’m not a big fan of widgets anywhere really – not on cell phones, not in Vista nor in OS X. I find them distracting toys for the most part.
The option I finally settled on was Menumeters which is informative, unobtrusive, pretty (enough) and highly configurable through its own pane in “System Preferences”.