First of all: this list is very interesting and looked promising, thanks for sharing this.
After looking a bit deeper into these projects, however, I have to say that a lot of them are fairly outdated and seem to be unmaintained. I tried to start a couple of them, and they won't even run since Meteor is not able to retrieve the packages.
The most interesting one (at least to me) was Exartu, which seemed to be maintained, but also did not run out-of-the-box since it requires an undocumented Amazon S3 API key. I think I will get that up and running, though.
To be honest, after this deep-dive, my gut feeling said: Well, if that's the crème-de-la-crème of mature open-source Meteor projects, then is Meteor really a "mature" development platform? After so many years, shouldn't there be more convincing samples out there that are actually used by the target audience (and not being shut-down after some months, like some of these projects obviously are)? Maybe Telescope is an exception, as I heard a lot about it in these forums, and I can't really judge its adoption rate.
Don't get me wrong: I am still quite enthusiastic about Meteor and don't regret my decision so far. But I am really wondering where the real "killer apps" are. The only "really serious enterprise" app I've seen so far is Kadira, but that one's directly related to the Meteor ecosystem.
(On my journey through these projects, I also encountered a quite interesting back-story on one of them: http://www.ryanglover.net/articles/proper-is-shutting-down-october-29th-2014/)