PostgreSQL has the option to turn off fsync and synchronous commits (http://www.postgresql.org/docs/9.1/static/runtime-config-wal.html). Does SQL Server has this option somewhere?
No, Sql server doesn't let you turn off synchronous writes to the log file. If you were able to do so, then you would lose ACID compliance.
If this is a "make it go as fast as possible" scenario, then a better approach is to analyze wait statistics to identify what the bottleneck actually is. Risking data corruption is never a good idea.