I started hosting sites a while back using Cherokee. For external sources (FastCGI, etc) it has an option to launch the process if it can't find one running on the designated socket or port. This is great because it means if PHP or a Django site falls over (as they occasionally do) it restarts it automatically.
On a new server using PHP-FPM I couldn't use Cherokee (it has a bug with PHP) so I've moved to NGINX. I really like NGINX (for its config style) but I'm having serious issues with processes falling over and never respawning. PHP does this sometimes but Django sites are more of a problem. I've created init scripts for them and they come up on boot but this doesn't help me if they conk out between reboots.
I guess I'm looking for a FastCGI proxy. Something that, like Cherokee, knows what processes should be running on which sockets/ports and respawns them on-demand. Does such a thing exist? Is there any way to build this into NGINX (for ease of config)?