If you want something more substantial than nylon then a nice polycotton Tatonka TC1 would work very nicely.
At just shy of 3kg it's not something you'd want to carry far but great for canoe trips etc.
Marty at Wilderness Logics designed the Wild River tarp for me as a group tarp for my river rafting trips. He was great to work with and the tarp that we came up with.....the Big Otter, is awesome. Exactly what I wanted. Here are a few pictures of the Big Otter (green tarp) and my WL Big Daddy (brown tarp) in action last week on the Main Salmon river in Idaho. The Big Otter gave us great shade for 8 people & one large dog, and kept us dry in a couple thunderstorms. This tarp is super easy to put up and take down, light weight, and sturdy. Marty does great work and you will get your tarp fast.