I've used copSSH for Windows in the past, which at the time seemed to be the most up to date port of openSSH for Windows. It's basically a subset of a complete Cygwin installation which includes remote cmd, bash and sftp. But I don't know that it is runnable from a flash drive.
The same goes for freeSSHd, which is a fair bit easier to set up, but based on another SSH implementation (probably not quite as thoroughly tested as openSSH).
Then there's Microsoft's Services for Unix which provides rsh but there's some openSSH port for it too.
Depending on what you're looking to do here, you might just temporarily boot something like Ubuntu or Knoppix off a flash drive and make your partitions available through that. Or put a VMWare Player on the stick with some Unix VM and mount your partitions into that. Lots of options really.