Ask HN: BI / Data Warehouse / Analytics Opportunities in Berlin?

In London there is a very large set of recruiters that supply freelance/contract opportunities. There is also a lot of dedicated job boards and websites listing contract roles.

I was wondering if anyone knows of a similar set of agents, contacts or job sites for contracting jobs in the Berlin or Hamburg areas in Germany?

It would be a bonus if the resources indicated whether Advanced level German language skills are required or whether English with intermediate German would be sufficient.