
Rainmeter is a customizable performance meter, which can display the CPU load, memory utilization, disk space, network traffic, time and many more things.
Rainmeter Features
Freeform skins

Supports Windows transparency

Plugin system for 3rd party support

Anti-aliased drawing routines

Works also as Litestep plugin

Has ability to hide on mouse over

Can stick to the desktop (i.e. doesn't hide with Show Desktop)

Skins can react to mouse events

Multiple skins can be ran at the same time

Can be controlled from 3rd party applications with !bangs