Database tables / fields you always use in your killer apps [closed]

Question

I'm hoping to tap into some collective experience here, so What (if any) utility tables, or common fields do you always include in your database design?

An example is that I always include an App_Errors table to store any uncaught exception information in, and an App_Audit table which stores all the edit information.

I've mooted (in my own mind) the benefit of including RecordCreatedDate and RecordLastEditedDate on each data table but not come to any conclusion as to whether or not the information really will be that useful.

To give the question a bit more direction - My current focus is globally accessible web application ( think social networking ).

Ta!

Answer 1

1 A table that contains a version number, so the app can easily check the version of the schema.

2 A table to hold arbitrary variable/value pairs, like a configuration file, but in the database. (You can put the version number in here....)