It's primarily for companies that want to sell us things to put on your cars, but nowadays, the car companies themselves are getting in on the action.
Chrysler came up with all sorts of fun things this year, partly to sell you their own add-on performance accessories, and partly to have a little fun while providing a look into the future.
"Show them some things that maybe we were working on," said Mark Trostle of Chrysler. "Try to engage their reaction, their support. It helps us know that we're doing things that they want to buy from us."
Some cars that come out of this could end up as production models or with features we'd find on them. Who wouldn't just love a Fiat 500 done up like a vintage hot rod? Don't submit your order just yet.
Other car brands play in this arena too including Toyota.
"It allows a lot of people here to exercise some creativity that you know they might not otherwise get a chance to exercise," said Keith Dahl of Toyota.
From a Prius customized with the help of Nascar driver Clint Bowyer to an ultimate fishing truck built on a Tundra, the SEMA Show is the premiere automotive specialty products trade event in the world.
One of Toyota's themes for the 2012 SEMA show was to show that they're still a company that can have fun. How much fun? Well they even did concept in custom vehicles based on family cars like the Camry and the new Avalon.
Most people don't tend to think of the Camry as exciting but a little customizing adds some pizzazz.
With help from the crew at Dub Magazine, extra "bling" and of course some serious sound was also added to a Toyota Avalon.
Most of these rides are a little far-out but inspiring creativity in the auto industry makes for some interesting cars, perhaps even in showrooms someday.