Proz is a community for translators and interpreters with a large directory of freelance translation jobs.
They also have something called the Blue Board where translators can check on the rating for ´outsourcers´, clients who have requested work in the past. This helps freelancers assess if they want to work with them or not.
Their is also the option to work on projects in a team, collaborating with other translators. You can ask to join another team or create a new one and invite others to join.
As as a translation and interpreting jobs directory, Proz is a great resource where members can find training courses and tools to help them in their work.