I know the question is quite old and already answered, but I hope this still may be interesting for someone stumbling upon this question.
I've built a Github repo which intends to provide several configurations for building and provisioning a Vagrant box without requiring to write a provisioning recipe from scratch.
For example, using the currently provided configuration, you can build and provision a box with:
- Ruby 1.9.2-p290, managed with rbenv and using Bundler for gems
- PostgreSQL 8.4
- MongoDB
Here is an introduction article on my blog.
Since this almost match the request, I felt it was worth adding this late answer :)