RainX is the stuff you spread apply to your windshield that repels rain, meaning that you don't actually have to use your windshield wipers.
Here's one Redditor's endorsement: First, it will last a lot longer than a few days if you follow the directions to a tee. If it's at all cool air temps when you apply it, turn on your defroster for a while to heat up the window. Helps a lot. When you get up to speeds that make the rain "skitter" off the windshield, stop using the wipers; this speed will vary depending on the angle of your window. [...]
Photo: Kjarrett, Flickr.com
Lastly, I've heard Aquapel makes Rain‑X appear as though a drunken monkey had smeared feces over your window in comparison. I can't personally speak to this, as I cannot afford Aquapel. Sounds fun.