Requires: Root access and Jellybean
User Management provides a nice GUI frontend to use the limited multi user support added in Android 4.1 Jellybean
IMPORTANT: Actions on the Primary user are disabled by default for your security. I do not know what will happen if you delete/rename that user. However, in case any of you want to try it out, the help screen has an option to allow changes to the Primary user.
NOTICE: The SD Card permissions are required to rename the users. I couldn't find a way to save to the file system, so I read the user's file using the cat shell command, edited it with the new name, saved it to the SD Card and then used the cat command to overwrite the initial file. It's hacky, but it works.
DISCLAIMER: While it has been tested and made as safe as possible, use at your own risk. Developer is not responsible for anything that happens to your device.
Removed ability to delete Primary user for your safety