Useful Portable [School-]Software

[Hitman]

Hey guys, can you recommend any useful programs that could come in handy during school when there's access to a PC?

Note that all programs need to be portable in order to run from an USB device, because installing software doesnt work on most of the PCs of my school.

- Open Office Portable
- Portable Firefox 4
- Portable VLC Player
- Wikitaxi, offline-Wikipedia
- Portable Notepad++
- Mozilla Sunbird (Calendar)
- IrfanView & GIMP Portable
- Sudoku Portable
- Portable 7zip

Do you know any more (portable) software that could be helpful during school, if you only have access to a restricted school PC?

Thanks in advance