Had a United A-320 captain do this once on a trip from PHX-DEN (TED flight). Before pushback, the Captain came out to the front galley, grabbed the flight attendant PA, and proceeded to make a very laid back (relatively quick) announcement with some interesting facts. Went something like this:
"...I am assisted by First Officer Johnson. He'll be doing the driving, I'll be working the radio's. Between the two of us, we have over 20,000 hours of flight time. In flight, we'll be crusing at 520mph, and we will burn 12,000lbs of gas during the trip."

I enjoyed the laid back announcement, and since it was before pushback, I liked how he through some interesting facts at us.
During the middle of our descent into Denver, the aircraft started down VERY fast and VERY steep. Seatbelt sign was not on yet. Suddenly we encountered SEVERE turbulence. Colorado mountain wave. Very violent. The girl next to me grabbed by arm and started freaking out. As a pilot with 100's of flight hours, and glider time in colorado mountain wave, I was still slightly concerned. Having looked the captain in the eye during his PA announcement was not only enjoyable to begin the trip, but very reassuring knowing he was incharge and going to get us down safely.

Thought I would share that.
P.S. I really like:
1. The UAL captains who chat on channel 9.
2. Pilots who make the announcement from the cabin. Good ole' Independence Air philosophy.