So I wrote Monocle. Monocle is written in Perl. It has no configuration files. No GUI. no web UI. Just a server, some commands to configure it, and an embedded database. It has reporting features that let you answer questions like, "Was our service down last night at 3:45 AM?", and "Was our response time faster the first week of June than the first week of July?", and of course, "What was our uptime for the month of January?" Anyone with an SLA on their services will appreciate these reporting features.
This is nothing revolutionary. Just a simpler design with the core features I think belong in a monitoring system.
If anyone wants to try it out, I put up a simple web page here. It's still in beta, so bug reports are most appreciated!