Download (or run, less than 1mb) the mini sftp server: http://www.coreftp.com/server/download/msftpsrvr.exe
Next:
1: Fill in the user/password fields with a user/password combination of your choice.
2: Select the port, and directory to give others access to.
3: Click start! Now other users can access your files via Core FTP client (SSH/SFTP option checked). Simply give them your IP, user and password.
More details: http://www.coreftp.com/server/
