It's funny to me to see "was cool" and "amazing this is still alive", because I absolutely love Asterisk. I cut my teeth building Freepbx boxes at a small/mid business voip provider in college before moving on to a different field.

To give an idea why I think it is so cool, my podcast offers neat things to folks who call in to leave a voicemail. You can listen to entire podcast episodes, explore a crude phone sound "museum", and if you're a subscriber to the podcast you are given the password to our party line, where you can talk to our hosts and other subscribers. I'm also building a choose your own adventure type game on our phone system using IVRs and things for our top tier subscribers to play.

We're not a phone-centric podcast, but it's super easy supplemental content to provide folks for cheap. It's also currently running in the raspberrypi specific release http://www.raspberry-asterisk.org/

There are other folks who absolutely rely on Asterisk for their shows, some that have been around forever, like the Phone Losers of America Snow Plow Show.