I keep seeing this in the sporting goods stores and was wondering if anyone uses this, on what gear items and what are your results? I may use it if it helps repel a light drizzle but I'd rather spend the money on gear if it doesn't.

I dunno about whatever it is you are seeing, but I keep a spray jug of nikwax tent and gear proof around, I use it on non-silnylon things like tents, but more often on my light nylon
primaloft parka shell, and on my windshirt. It adds a reasonable degree of water repellency without turning it into a baggie that
I sweat in. I re-dose it any time I wash it.

Just remember that water repellent is not the same as waterproof! DWR (durable water repellent) material resists minor drizzle and drip, but definitely not heavy rain.

That being said, I've found that in a drizzle or in warm rain, I'm better off either to wear a wind shirt or just get wet. Lightweight nylon or a wicking baselayer top dries really fast from your body heat, unless it's too cold. Under these circumstances I get wetter sweating inside so-called "breathable" rain gear. Of course I put on an insulating layer under rain gear when I stop hiking, either to rest or make camp.

As Phat says, you need to renew DWR with spray (or a variety of wash-in or rinse-in products) after washing. This includes "breeathable" rain gear, wind shirts and the outer shell of your sleeping bag.