Nerdtool!

Rainmeter is a desktop customization platform. Through Rainmeter, you can enhance your Windows computer at home or work with skins: handy, compact applets which float freely on your desktop, much like Windows Sidebar gagdgets, or dashboard widgets for the Mac. Rainmeter skins provide you with useful information at a glance. Its easy to keep an eye on your system resources, like memory and battery power, or your online data streams, including email, RSS feeds, and weather forecasts. Many skins are even functional: they can record your notes and to-do lists, launch your favorite applications, and send your tweets to Twitter - all in a clean, unobtrusive interface that you can rearrange and customize to your liking. »

Conky is a free, light-weight system monitor for X, that displays any kind of information on your desktop. Originally a fork of Torsmo, Conkys torsmo-based code is BSD licensed. New code in Conky has been licensed under the GPL 3.0.

iStat is a series of system monitor apps. It's available in different versions: iStat Menus, iStat for iOS and iStat Server as a companion application to the iStat for iOS app that lets you remotely monitor your computers (free for Windows and Mac).

How many times have you walked up to a system in your office and needed to click through several diagnostic windows to remind yourself of important aspects of its configuration, such as its name, IP address, or operating system version If you manage multiple computers you probably need BGInfo. It automatically displays relevant information about a Windows computer on the desktops background, such as the computer name, IP address, service pack version, and more. You can edit any field as well as the font and background colors, and can place it in your startup folder so that it runs every boot, or even configure it to display as the background for the logon screen. »

Plasma Workspaces is the umbrella term for all graphical environments provided by KDE. Plasma separates components into "data engines" and their visualization counterparts. This is intended to reduce the total programming effort when there are multiple possible visualizations of given data; and to make it easier for the data engine and the workspaces to be written independently. Currently there are three workspaces being developed: Plasma Desktop for traditional desktop PCs and notebooks, Plasma Netbook for netbooks, and Plasma Active for tablet PCs and similar devices. »

GKrellM is a single process stack of system monitors which supports applying themes to match its appearance to your window manager, Gtk, or any other theme.

The BitBar app lets you put the output from any script or program right in your Mac OS X menu bar. And it's completely free. An impressive number of plugins have already been contributed by a wide range of developers just like you, and this site makes it easy to find them.

GeekTool is an application for Mac OS 10.6+. It lets you display various kinds of information on your desktop via 3 default plug-ins:

XWidget is a free desktop customization platform. It’s light, handy with powerful visual widget editor and very subtle animations. The Android page is found here: http://android.xwidget.com/

MiniUsage displays various data like CPU usage, amount of network flow, battery status and process names which uses much CPU time in a menubar. It takes little space and can display various data, so it's suitable for notebook.

Übersicht lets you run system commands and display their output on your desktop in little containers, called widgets. Widgets are written using HTML5, which means they

Create you own designs and display any data you need, at once, and with wonderful animations too! If you were looking for Rainmeter or Conky on Android, this is it!

BGINFO for X, also called BGINFO4X, is a clone of the popular program BGINFO for Windows created by Sysinternals.You can refer it as BGINFO for Linux, BGINFO for Unix, or BGINFO for X-Windows, which has derived to BGINFO4X (BGINFO for X).

This little application displays system information on your desktop in a similar way to some other desktop information tools. Unlike others, this application looks like wallpaper but stays resident in memory and continues to update the display in real time. Uses very little memory and nearly zero cpu. Perfect for quick identification and walk-by monitoring of production or test server farms. Everything is customisable including language.