Rain-X is the most well-known product and has been doing this for around 40 years.
A quick search shows
AutoExpress did a test in 2006, so I'm sure there's many more products on the market now.
Almost every other 'detailing' brand has a 'miracle' glass treatment that offers similar results but at varying prices (from £1 for a 250ml bottle to £50 for a 10ml 'treatment'). There's stuff from Aquapel, Rain Magic, Farecla, Turtle Wax, Meguiars, DiamondBrite, Mer, Ombrella, Carlack, Collinite, Nanolex, GTechnic, Duragloss, etc. As a DW user you can easily do a search on there to see reviews/feedback on these treatments.
Most claim that they last for months, but that's only true if you never actually go out in you car and drive it in the rain - and at some point you have to use your wipers (and thus remove some of the coating) as either you're going too slow for the beading water to be blown up the screen, or the water is not clean and leave dirty residue behind.