Does vibe.d have a CI server set up to make sure builds don't break, and stay working across different compilers? I've got a feeling that'd be very useful for vibe.d to mature further. I know that I've run into incompatibility issues between DMD, DMD-Head, and LDC, and a CI server might mitigate some pain for many others to. I'm not sure how difficult it'd be to set up, however.
A lot of open source projects, both big (Ruby on Rails) and small (lots of Rust libraries now) make use of free CI hosting at http://travis-ci.org. Perhaps that would be a good place to start?
--Dylan