currently addicted to:

Neutrogena Instant Nail Enhancer. I think I picked it up because it came with some lip moisturizer or something, but I'm a convert. The product is clear; you spread it on your nails to give them a healthy shine. It claims to reduce peeling.
Well, I didn't much believe that claim (you wouldn't believe how many anti-peeling products I've tried) but I figured it was worth a spin. It's worth. Previously, no matter how careful I was with my nails, they would peel and split horribly. I couldn't grow them past the tip of my finger. Now they've stopped peeling and they're long and strong. (And I don't have to paint them to make them look acceptable.) And applying this stuff is the only change I've made: no dietary changes or new vitamins.
I know I sound like an infomercial, but I'm really loving this stuff. Check it out.
$6.49 at drugstore.com (but I got mine at Target)