Patagonia Torrentshell 3L

I don't often shill for products (actually, maybe I do) but this jacket is so good, I couldn't resist. If you're looking for a light-weight, rain-shell this is an absolute must-buy. It will set you back about $150 but it's well-worth it instead of buying a crappy one that cost half as much and having to replace it because it sucks. I've owned this jacket for about two months now and already had the chance to test it in heavy rain at least a half-dozen times (I live in Western Pa. and it's spring).

The best things about this jacket:

• The 3-layer nylon is super water-proof, and thick enough so you don't get that "sticking to you" kind of feeling, even when things get super wet.
• It's thick enough to trap heat yet somehow doesn't trap moisture. In other words, you can wear it as an extra "warmth" layer without getting the above-mentioned, slimy "inside of the rain-coat" feeling
• Can be used as a wind-breaker
• Worn over a fleece, it's just about a perfect combo for most Spring/Fall outdoor activities where rain might be involved
• Good, strong elastic tightener around the bottom seam, to keep out wind and water

Personally, I bought this jacket to wear over my waders when I fish, making me completely waterproof and impervious to the rain. In Western Pa. you have to fish in the rain often. If you wait for a nice day, you might not get much fishing done. But in this jacket, I have no worries about the rain. When I take this jacket off after a day of fishing in the rain, the inside is utterly dry. Strong, tight elastic draw-cord is great for wading in deep water. 

Not sure how it will function in warmer weather, but there are armpit zippers so you can open get some ventilation on warmer days and still stay dry.