Moss!

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.

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/

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.

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.

Nerdtool allows you to display many things directly on top of your desktop; weather reports, headline news, and system vitals are just a few uses.

Motherboard Monitor is a utility designed by Alexander Van Kaam for Microsoft Windows that provides live information about the state of a motherboard and other hardware, including temperatures, voltages, fan speeds, and more.

AveDesk is a program that will give you the possibility to have icons on your desktop which could update themselves. Each icon of Avedesk is in fact a desklet, a little plug-in that can virtually do anything. A desklet can be just a regular shortcut, a mail checker, a calendar, a clock, etc.

Cysboard - A lightweight system monitor similar to conky with html and css for themes