About this photo:

This is a curious spider. It weaves a web along the branch, which it is doing in this photo, then lies on top of the web stretched our along the branch waiting for something to blunder into the web. Another photo in this collection shows this spider lying in wait. 

Based on the description in How to Know the Spiders, I think this may be Tetragnatha versicolor.

Notice the long chelicerae on this spider, which is the basis for its name.

We saw this spider working in a small tree along Barton Creek near our house.