I think it was a few years ago I registered an AS# in DN42. IIRC my setup was OpenVPN to a few peers that I dont remember how I found, but one was in the US and one was in France and I think there were others. Through the tunnel I was running a virtual Cisco router and peering with folks running Quagga or strongSwan. No one else seemed to be on Cisco.

The whole thing was slow, communication was crappy, but boy was it fun! As a young NetEng this was an awesome opportunity to learn BGP better and mess with all the BGP settings.

Apparently there are folks that run all kinds of services over DN42. I never really dug in enough to look though.

EDIT: I dug through my email, I was AS#4242420690 (I was having fun here) and I think I was assigned a /28 or /29. My setup was particularly slow because I was nervous to peer from home so I used a VPS in Czech Republic as my VPN pivot point. OpenVPN from VPS to home where the Cisco router lived and OpenVPN to the BGP peers. I then could communicate from the Cisco router through the VPN to the VPS to the remote peers on the other VPN through the VPS. I definitely over complicated things but it was fun!