I use an 8X10 tarp which serves as both a ground cloth and the shelter. Here's a photo:
![](https://sphotos-a.xx.fbcdn.net/hphotos-snc6/182185_4249922964724_875213191_n.jpg)
The tarp is great because it can be set up many different ways, some of which require a groundcloth, some of which don't. And even this setup can be adjusted a bit depending on weather.
This site gives some interesting info on the many ways one can set up a tarp. Some make more sense than others and frankly the diagrams can be a little confusing. But I have used two different setups to great effect.
http://www.equipped.com/tarp-shelters.htmThe best setup is a 10X10 or 12X12 but its hard to find pre-made tarps in square format (with grommets for tie-downs). Have been looking at using Tyvek though its hard to find in 10 feet widths let alone 12. 9 is the more common dimension. But there is an ebay seller who has reasonably priced "kits" including custom cut Tyvek and various tie-down options. Just search "camping tarps."
I find that when I am out on the trail, I have LOTS of time to play with how to setup my shelter (though where I live I am rarely in danger of being rained on unexpectedly) so I haven't worried too much about figuring it all out in advance. Though certainly you should have at least one go-to arrangement you can pitch quickly just in case. I practice in my yard...
Ride on!