More seriously, I use mine mainly to log into computers, get into my house, get into the building at work, get into my locker and share contact information. You can also start your car with it. That’s the main uses for RFID implants usually.
And of course, if you’re technically inclined, you can have good fun goofing around with custom interfaces for your implant, or slighty more useless things - like here for instance, my pathetic attempt at RFID music 