For those of you who don’t already know about free and Open Source software, there are many software programs that can do what you want for free. You can check out all of the free software at sourceforge.net.
A great thing about open source software is that you have access to the source code and if you know anything about programming, you can customize the program the way you like it.
Some great examples are:
-Linux instead of Windows
-Openoffice.org instead of MS Office
-GIMP instead of Photoshop
There’s an entire community built around free software. The community is called the free software foundation and more information can be found at their website. http://www.fsf.org/
Also, check out the free software portal on Wikipedia, there are many great links there.
A list of free software alternatives to the programs that you already use can be found here, I think this is a great list despite all of the negative sounding comments where people decided to pick it apart.
Many of these applications are even becoming web based.
MS Office – Google Docs
SharePoint – Google sites
del.icio.us as a bookmark manager.
MS Exchange – Google APPS (not entirely the same but you get the idea.)
Microsoft streets – Google Maps