Tricider.com allows teams to make decisions collaboratively on a variety of topics using a web-based interface.
Currently the site doesn’t require registration and it’s completely free. Team members specify what they want to decide and they receive an URL that can be used in order to submit answers or to vote on existing solutions.
The project is relatively new. Nevertheless, the site impresses via its simplity, clarity in explaining what it does and how to reach those goals, and the fact that everything is login-less (however the URL for deciding something contains a secret token, allowing only the people you invite to actually participate).
Tricider’s creator is based in Berlin, Germany and its interface is available in both English and German. For decisions where trust is not an issue, the simplicity of the interface makes it an ideal candidate to be used for reaching a consensus in a collaborative fashion.