Just thought I would ask if anyone has put together a more complete list?
I take insult to that comment. The 400+ games already supported are a result of constant hard work by a handful of very dedicated volunteers. This is over the course of several months in secret and several more months public. We have to research each game, not trusting any of the "normal" game information soruces and instead having to find original manuals and other documentation and comparing it with the actual source code of mame to make sure the input methods match. Your not going to find a more complete list... or even a less complete list anywhere. That was the entire point of the project.

Regardless the ini file format is proprietary and only fully understood by yours truely. The xml format is also proprietary and only fully understood by sirpoonga. So even if you do find an alternate source, as it would be generated by hand, it probably wouldn't have the correct structure to use it in the viewer.
I don't mean to be rude, but as you unitentionally were I guess we are even.
It's real easy to users to underestimate the amount of work it takes even for the most modest of projects, so I can understand why you asked. But this is a MASSIVE project, if you want more entries then your best bet is to do some entries and encourage others to do so as well.