I'm mildly obsessed with license plates. Sure...they are meant for your car, but design is all about breaking the rules. License plates are fairly inexpensive, extremely lightweight, and vary in color to coordinate with any space. Use them on a wall for a great, rustic look with pops of color (LOVE the orange and green of Florida and the red and white of Maine), or use them on a book shelf as a fun little accessory.
We have some license plates that have been our cars that mean something, and some that are just aesthetically pleasing that we have picked up along the way! Whichever you prefer, have fun with them, use them in a fun new way, and if you don't love it...change it!