Stephen LaBerge proposed two ways to prolong a lucid dream … The second technique is rubbing one’s hands … Results showed 90% of dreams were prolonged by hand rubbing.

(via http://en.wikipedia.org/wiki/Lucid_dream#Reality_testing)

I read this a few minutes before going to sleep, and the hand-rubbing trick worked perfectly for me.  I did get overexcited about the lucidity, and woke up a little while later, but the fact that I was able to recognize, and prolong the dream was a definite personal victory.