I'm in the "keen to go" camp, too. I got to sit on a New York City grand jury. Grand juries, for those of you unfamiliar (I only had a hazy understanding of it), decide if someone accused of a crime will face a trial. If the grand jury indicts you, you're going to have a trial. I learned everyone gets indicted - because only the prosecution presents evidence - and also had my eyes opened to a wide variety of points of view concerning the justice system.
There were 23 people on the grand jury, but it only took 12 to vote to indict someone for them to be indicted and have to go to a trial. Some people were hard a££es about it and voted to indict everyone, and on the other end there were a couple that wouldn't vote to indict anyone.
One suspect had been pulled over after running a red light in Manhattan at 3:00am. According to the arresting officer, the driver had 3 guns and a bullet proof vest on the passenger seat in plain view. One of the jury members said she wouldn't vote to indict the suspect because, "What were they looking in his car for anyway?" (He got indicted anyway.)
We also got to hear about a police shooting, and decide whether the police officers who had fired their weapons were justified (we decided they were). That was very cool, as we heard from different people involved in the incident over a few days each week (the jury lasted a month), so it was like following a really good cop show.

I got picked to sit on a military court martial when I was in the Air Force, but I was the supervisor of the wife of the accused, so I was excused. Bummer.