SQL Server 2008 Table Maintenance - Rebuild, Reorganize, Update Stats, Check Integrity etc
Usually you'd do weekly or daily depending on your usage and maintenance windows.

You pretty much never shrink, especially not scheduled.

For rebuild/reorganise and statistics there are scripts (such as SQL Fool's one) that do a better job.
Note: reorganise and rebuild are not exclusive but work different ways. 3rd party scripts can choose the best option (based on fragmentation).

We use weekly index/DBCC and daily statistics. And never shrink.

From Simple-talk: Don't Forget to Maintain Your Indexes