How often should I run integrity and consistency checks on SQL Server 2008? Before updates of our application, I run some checks on the database like CheckAllocations and CheckCatalog, so I know the database is in good shape before the update scripts get executed.

What is recommended for checks like that? How often should they be executed?

Do we need more checks besides these two? 

We used to run the CheckIdentityValues as well, but I removed that, because that method will be removed (according to MSDN).
For me, it depends on your maintenance window and usage. It takes time and resources to run the DBCC checks so you want to minimise imnpact on a running app

If you can run it every night, do so. Otherwise weekly. 

Or monthly if you really are 24/7.. but then I'd be running DBCC on a restored database as an extra check.

And you have to consider other maintenance too: indexes and statistics in your window