dat is an open source tool that enables the sharing of large datasets, allowing for a decentralized collaboration flow similar to what git offers for source code.
It isn't quite ready for prime time yet, but if you want to play around with the beta version please check out these slides or read the readme of the dat repository on GitHub.
If you want to support the project (I currently have a small bit of grant funding from the Knight Foundation which lasts until February 2014) then request some stickers and give them out to people who support open data. If you have a recommendation for an organization that might want to sponsor further development on dat in the future please get in touch.
Here's a 10 minute intro to dat: