OPSEC
Poncho that folds up into a small-ish pouch, covers down below your knees, unsnaps to house a ruck sack, will protect your weapon as well and spreads out into a tent or tarp. Comes in multicam.
http://www.grampsleather.com/o-p-s-e-c--details.html
I've had one for years and it works great. I'm not too big on fighting in it, I'd rather have like s Crye wind liner or something for that. But for hunkering down, protecting your gear, pure ease of use, or hiking in the rain, it's great.