Okay, I'm not sure that this qualifies as a "gadget" but I have to list it here because it is really, really cool! Have you ever thought about how nice it would be to sit in your backyard and watch a movie? Well now you can turn your backyard into a drive-in - or a "sit-in" - with a giant inflatable movie screen! You'll be the hit of the neighborhood with one of these. You can buy just the screen, or a whole kit that contains, the screen, projector, DVD player, speakers and all and the price is very reasonable for what you get. When it's not in use, just let out the air and store it away.
If you're renovating your yard, or looking to add to your backyard's atmosphere - or looking for a great Father's Day gift! - check this out. Click on the picture to learn more about it. You can also find more information and examples here: Inflatable Movie Screens.