You can use it for different purpose like demonstrating videos for any software program, creating video tutorials for school or college classes, creating video based information products for selling purpose, recording of new tricks and techniques discovered by you on your favorites software program, creating a set of videos to solve question mostly asked by users etc.

Cam studio is completely free your personal and commercial project without any limitation.

Features
Records PC activity in AVI format and SWF (for directly putting at any webpage)format.
You can capture the screen region in three modes (Region, Fixed region and Full screen).
Site offer for Cam Studio Codec to decrease file size.
Record high quality videos.
It is very customizable .you can even pick an image to display instead of your cursor.

Requirements:-Windows 95/98/Me/NT/2000/XP/vista
Download free cam studio
Author home page
Quick use
Click on record button (showing in red color).
It will display a rectangular box with a pointer in middle of box (Box shows Left, Top, Width and Height Dimension)
Click the mouse pointer at the region of screen which you want to record
Recording will be start
For stop it, right click in cam studio icon (notification area) and click stop.

site home page

Now it has become very easy to create technical diagram for electrical engineer, a computer programmer and for network administrator. Using Dia people can draw UML diagram, network maps, entity relationship diagrams and flowcharts. New shapes can also be created by writing simple XML files, using a subset of SVG to draw the shape. Creating diagram using Dia is more flexible and free from hassle. An electrical engineer use Dia to create a diagram showing how their circuit works. A computer programmer may use Dia to create a flowchart to show the execution path o their programs and a network administrator shows the execution path of their program through diagrams created by Dia.

Some Features
Page printing (Dia support saving and printing to printers. If you have gnome-print installed, the printing is very easy)
Export too many formats (EPS, SVG, CGM and PNG)
The ability to use custom shapes created by the user as simple XML descriptions
Customization (Dia can be changed allowing the user to make Dia fit more to their needs.)
Examples

Supported operating system: windows (Windows 2000, XP or Vista), Linux
License: Dia is a GTK+ based diagram creation program for Linux, UNIX and Windows released under the GPL license.

Direct Download Dia for Windows version of 0.96
Publisher site for others version download

Switch to the Hydrogen Alpha view to see the distribution and illumination of massive primordial hydrogen cloud structures lit up by the high energy radiation coming from nearby stars in the Milky Way. These are just two of many different ways to reveal the hidden structures in the universe with the WorldWide Telescope.
Requirements :- Windows XP/Vista, 2GHz CPU, 1GB RAM, 3D-accelerated video card with 128MB VRAM, 1GB disk space
Download free  WorldWide Telescope

Features include:
-Detailed information on each element
-Details of isotopes and allotropes
-Details of important compounds
-Details of reactions with water, air, halogens and acids

-Images for each element (300+ images in total)
-including valence and crystal stucture diagrams
-Glossary of terms
-Graphs of important element properties
-Biographies for the important scientists and element discoverers
-View the states of the elements at any temperature (from 0 – 6000k)
-XP style support
-Search through all content
-Electron shell diagrams of each element
-Atomic width diagram
-Toolbox, 330 physical constants and over 6400 formulae
-Element names and the majority of the applications buttons are now available in eight different languages. -Unfortunately there is just too much text for me to translate (100000+ words).

Click here for free Download