I'm very proud of two my projects dedicated to Ruby community - rubyflow.ru and rubyjobs.ru.
The community blog dedicated to Ruby language.
The job board with Ruby/Rails related vacancies.
It's a simple to use and slim (~150 LoC) library to work with oEmbed format. It has no external dependencies at runtime. All you need to have is Ruby itself.
The add-on was featured on Ember Weekly.