Undocumented Stored Procedures

Apparently there are extended stored procedures which are not documented in the Books Online. In this post I want to create a list of those stored procs with links to articles about how to use them. So far I have only one proc, but I will update this post as soon as I come across more.

• xp_ReadErrorLog (SQL Server 2005)

I don't think this one is an extended proc, but also undocumented:

• EXEC sp_MSForEachTable 'EXEC sp_spaceused [?]' - It allows one to execute a T-SQL statement against each table in a database.