Conky is a free, light-weight system monitor for X, that displays any kind of information on your desktop. Conky can display more than 300 built-in objects, including support for a plethora of OS stats, support for many popular music players, and Lua scripting. Conky can display information either as text, or using simple progress bars and graph widgets, with different fonts and colours. With some clever configuration you can use Conky to make some amazing system dashboards.
Runs on Linux, FreeBSD, OpenBSD, DragonFlyBSD, NetBSD, Solaris, Haiku, and macOS.