I really want to know if there is a System Monitor lens out there. If this doesn't exist, it would be awesome to see system properties in a lens such as HDD usage, RAM, and another properties.
No, for other lenses that are available see What lenses for Unity are available?, better use conky for that feature. Otherwise System Monitor Indicator are also available, I guess for that matter.
Try OMG! Ubuntu! - Tag Articles: conky for good conky's, that are otherwise available.