Rohos Mini Drive is a free tool to create partitions in a USB pendrive. This way you can access this partition via a password you choose. Rohos Mini Drive shows, in Windows Explorer, a new drive that lets you save your files there. The program works with the AES 256 bit standard.
You have the option to search the drive looking for errors. If you want, you can also change the partition size (and even format it). Rohos Mini Drive requires no type of adminstrator priviledge to open the partition: just type in the password.
It is easy to configure and use, and is completely free.