HN user
tonydewan.com
Michigan/Ohio/Pittsburgh is a really weird grouping. 2 states from the midwest, and a city from Pennsylvania. I get that they're sort of geographically colocated, but there's no way Pittsburg will have more people represented on HN Indiana/Illinois/Kentucky.
...and http://paperplane.io
Also: http://paperplane.io
http://paperplane.io is a similar service that I've been working on.
For the record: this was made before GitHub pull requests worked with the same repo, and before the event API. It hasn't really been touched since.
I do agree that it's not ideal for the review request to be enshrined in commit history. We've not used this for some for that reason.