A client wanted to add a description to each of his product categories, such that the first built-in description would be above the product listing, and the second description would be below the product listing.  Rather than have them create static blocks for every category, it was obvious that I’d have to create a new category attribute.

Fortunately, I stumbled upon one possible solution.  The method doesn’t involve creating a full-blown module, rather, just a few database modifications using phpMyAdmin.

Summarized, the process comes down to:

1. Create a new row in the eav_attribute table, one that mimics a category’s meta-description attribute with everything being the same except for a unique identifier and a label.
2. Create a new row in the eav_entity_attribute table, to provide a sort order for your newly created attribute, following in the format footsteps of the existing rows.

For the fully detailed procedure, see Create Custom Category Attributes with phpMyAdmin