I got them about once a year or so for a few years, always sent it in and when I called the number was told I wasn't needed.
Then two years ago, I got one and was told to come in. I went, wore a tie, and hoped like hell to get put on a jury. Many people tried to get out of it, saying they were biased for this reason or that, or just asked to be excused. I got picked in the last round of questioning to serve as a backup, in case one of the 12 jurors was unable to continue, I or the other backup would move in. This meant I went through the entire process as if I was a full juror, but I did not end up deliberating with them*
The trial was an illegal weapons charge, interestingly enough. I greatly enjoyed the few days I spent going through this process. Our justice system affects all of us. I can speak more fluently about the Zimmerman trial than many others. I can appreciate some of what is going on with the lawsuits against the SAFE act. Understanding how the system works gives me a unique perspective on the concealed carry of firearms and what will happen if I am ever arrested for using them. For me it was fun too.
I value my experience on a jury, it made me a more knowledgeable person about a huge part of our society, and I did my "duty to society". I liked it so much, I checked the box waiving my 7 year window where I couldn't be called. I would do it every 3-6 months if I could.
*This is by far the worst way to serve on a jury, because you are subject to all of the rules (no discussing the trial, have to be there when the jury is), but you don't get the "money shot" of finally getting to deliberate. You listen to all the arguments and form your opinions over days or weeks, and then aren't allowed to share them with anyone or play a role. Instead you sit in a room with the other backup juror, still unallowed to discuss the case, and play games on your phone until you die of boredom**
**Wait! I lied, we weren't allowed to have our phones.