Mine would include:
- Fully automated algae farm
The datacenter would function as "community memory", storing zines, music, movies, and whatnot that the people in the local neighborhood (I think the best structure would be some sort of apartment building - hopefully modified to be less atomized). The biohackspace and hackerspace would allow residents to develop science and technology to better their lives in whatever way they so choose, contributing the information yielded back to the community memory.
The other thing the datacenter (and this really only needs to be one or maybe two computers) would do is provide a local-area ISP that would facilitate maximally high-speed communications between anyone in the local area network. This should encourage sharing and collaboration.