Some of the below may require special extraction, or an initial install, to be able to copy the files to your USB drive. (Universal Extractor and Inno Setup Unpacker come in handy for such things.)
- Rogue Remover gets rid of rogue anti-spyware/adware programs.
- Winpooch Watchdog detects system modifications and includes real-time anti-virus.
- ClamWin Portable is an open-source anti-virus scanner.
- Avast! Cleaner is a virus removal tool.
- Small CD Writer (English Version) is a great single file program for burning CDs.
- Auslogics Disk Defrag is a nice GUI-based defrag program.
- JkDefrag has commandline options and does all disks in one run.
More to come another time...