Here's some of the best free software I've come across.
http://www.uraniumbackup.comUranium Backup: This is a full-featured backup program, capable of backing up across a network, or to local drives, tape drives. It also can compress data, burn to CD or DVD, and has an elaborate scheduling and file selection system.
http://www.educ.umu.se/~cobian/cobianbackup.htmCobain Backup is not as complex as Uranium, but does support backup to FTP.
http://www.gimp.orgGimp: Freeware photo editing software with hundreds of plugins available.
http://www.openoffice.orgOpenOffice: Freeware alternative to MS Office. Includes spreadsheet, database, document, and presentation editing software, along with and advanced calculator and publishing software.
http://www.realvnc.comReal VNC: Software for remotely controlling computers across the network. This is a must for any home network.
http://mediacoder.sourceforge.netMediacoder: Freeware video transcoding software.
http://www.context.cxFreeware text editing software with many highlighter templates. Designed with programming in mind.
http://keepass.infoKeepass: portable, yet secure password vault with built in password evaluating and generating.
http://www.deepburner.comDeepburner: CD/DVD burning software.
http://www.mozilla.comFirefox: Freeware web browser with built-in popup blocking.
Thunderbird: Freeware Email/Usenet client, simpler and more secure than Outlook.
http://filezilla-project.orgFilezilla: Freeware FTP client and server. Nice drag-n-drop interface.
http://audacity.sourceforge.netAudacity: Audio editing software, complete with tone generator.
http://www.blender.orgBlender: Freeware 3d modeling, animating, and rendering software.
http://www.vim.orgFor text editing, especially programming-related, I like gvim.
http://www.portableapps.comOne of my favorite "applications" is Portable Apps, which lets you run a whole lot of software (much mentioned in the original article) from a Portable USB "thumb drive" without having to install it on the PC. This can also be a great way to try out new software without the worry of it leaving all kinds of crap on your machine.
http://www.pidgin.imA good multi-protocol instant messaging client
http://www.videolan.orgExcellent video viewing application
http://www.joejoesoft.com/cms/showpage.php?cid=108Rename Master: Batch filename/extension editing tool. It can add or remove portions of filenames, capitalize by sentence or by word. Tons of features, and is both free and portable.
http://www.fookes.comEasy Thumbs: An excellent tool for making thumbnails of images in batches.
http://www.cyd.liu.se/~tompe573/hp/project_sfxr.htmlSFXR: A lightweight yet effective sound effects generator.