Libman: I'm the author of Hox, and I think it would make a decent starting point for a basic web framework. The router is barebones, but probably usable for many projects; there's a hook-system which allows plugins to run code before/after. My main reason for not playing more with it was I was having trouble integrating the H2O-event loop in Nim. Any other I/O (e.g. Postgres) would have to be blocking which kinda works against the idea of using an event loop. I guess you could use a thread pool and run Postgres queries there before you dispatch the result back into the event loop.
Honestly I was hoping Nim would have a way standard way doing async I/O (which I could hook into) by now.