For awhile I used a heavy duty poncho. Real heavy duty. Weighed quite a bit and didn't pack well.

Benefits: Ground cloth
Rain gear
Emergency shelter
Pack liner
Signaling (inside was yellow)

Draw backs: What if I need more than one at a time....?
_________________________
http://rrooa.blogspot.com/ <-- There's my two cents. Reviews and other things so go trough the blog archive. Check it out and leave comments.