The spider was exploring various part of the bench. Here's a view from above showing the orange sides of the abdomen.
Eventually it spent some time at the lower right corner of the bench.
It turned upside down and started releasing a silk thread!
Spiders often do this hoping to snag the loose end of the thread on a nearby object. I thought about what might be to the right of the bench. "Hmmm...there's nothing to the right of this bench...except my leg."
(I was sitting on the ground with my right leg up while trying to photograph the spider.)
The spider turned around and tested the thread to see if it had been anchored. I was looking through the camera the entire time, so I couldn't really see where the silk had landed.
Then the spider jumped on to the thread (using it like a zip line).
And this is the next picture I got:
The silk had found my leg! And now I had a jumping spider on my jeans!
What a beautiful little spider. I was happy to be a part of its afternoon adventures.
ADDENDUM (31 JANUARY 2013): Thanks to Dick Walton for helping to identify this as a Red-backed Jumping Spider (Phidippus johnsoni).