We noticed a problem when customers mistyped their state name while filling our shipping or billing address information. If selects United States as the country and types in the name of the state incorrectly, OsCommerce checks the name against the names in the database and returns the customer to a prefilled form with a state name drop down menu replacing the previous text box. The default state is Alabama. If the customer fails to read the error message at the top of the screen and simply clicks "continue" without verifying their information, Alabama is instantly set as the chosen state. Had the customer actually read the error message they would have changed the state and been all set.
I wanted to change the default value in the state field to "Please Select a State" but I couldn't find any mods or add-ons that addressed only this issue in a simple fashion. So I made my own fix. This fix only modifies the "zones" table of the database and requires no modification of the OsCommerce code. It is working without a hitch in my store and my store has been modified so many times that I don't remember all of the mods I have in it.
The attached text file describes the process of modifying your "zones" table and includes a copy of my "zones" table with the modifications already made.