I agree that this is needed. I've been using Vagrant for quite a while. I've used it for a large number of projects, almost all of my projects have a Vagrant environment. In spite of all of my usage, every time I start a new project, it always takes me a long time to figure out how I'm going to setup the provisioning. I would love to have some sort of directory for Vagrantfiles. Most likely, this would only be a starting point, but even that would be a huge improvement.
There are a couple of solutions to this problem, PuPHPet and Rove but, they aren't enough. PuPHPet is focused on PHP, even if it is extended to include other languages, the generated files are horrendous. Even if you wanted to use PuPHPet as a starting point and extend it, it would take way more to extended it then to start from scratch. Rove has a different problem. I still haven't quite figured out how to make it make a complete environment for an app.
I'm up for building it. Let me know know if you're interested.