Box.net - 5GB of free online storage (more can be purchased) that can be accessed and uploaded from your PC or mobile.
Dropbox - Another online storage solution, but a lot more popular than box.net despite offering a smaller amount of 2GB storage for free. Again this can be installed on your PC or mobile.
ThinkFree Office Mobile - View/edit/create documents (in all these MS compatible formats: DOC/DOCX/DOT/DOTX/RTF/TXT/XLS/XLSX/CSV/PPT/PPTX/PPS/PPSX/POT/POTX) on the move and get 1GB to store them online. Also with a PDF viewer.
erkie.github.com - Useful for letting of steam. Destroy your favourite, or least-favourite, websites... asteroid style.
BitDefender Quickscan - Run a virus scan in your browser. Good for checking if your antivirus software might have missed something.
Panda ActivScan - Another free online antivirus checker that works with Windows 7 among others.
Academic templates - Microsoft office templates for teachers.