Browser: Mozilla's Firefox
FTP: FireFTP, an excellent add-on for Firefox. (If you do not use FireFox, you need FileZilla--even if you have FireFox, you need the awsome capabilities of this free ftp client: FileZilla)
Spyware: Spybot Search & Destroy
Office Software: OpenOffice Alternative for Excel. Word, PowerPoint and Access that in many ways supieriour. And, for that extra comfort, it can open and save in native Microsoft Office formats.
Anti-virus: Free anti-virus software, and it is good.
Create zip and self-extracting zip files: ZipGenius.
Income tax: TaxAct.
ICO (icon) Maker/Converter: Imagicon
Backups: SyncToy
PDF Maker: PDFCreator We now suggest CutePDF Writer Also, OpenOffice (see above) will generate pdf files.

Beyond most users, but for those who know what a codecs are and why they might need them: Codecs