rstat.us is a microblogging site built on top of the ostatus protocol.
Just do this:
$ git clone https://github.com/hotsh/rstat.us.git
$ cd rstat.us
$ heroku create --stack bamboo-mri-1.9.2
$ git push heroku master
Bam!
This is nowhere near done. Jump on Freenode and ping 'steveklabnik' if you want to contribute in some way.
First off: you will need MongoDB (www.mongodb.org). They have a quickstart guide for getting it installed and running.
Then do the same as above:
$ git clone https://github.com/hotsh/rstat.us.git (or your own fork, if applicable)
$ cd rstat.us
Copy the config file; if you have actual Twitter API keys, you can add yours, but this file just needs to exist for the server to work.
$ cp config.yml.sample config.yml
Then update your gemset:
$ gem install bundler && bundle install
And instead of using heroku, start the server with sinatra:
$ rackup