I'm not certain if this is the proper forum to add this...but here goes.
I am building a rather extensive social media site that is very "user contribution" based. As such I would like to be able to include the capability to allow users to add their own categories. Is there a way (unbeknownst to me currently) that a field (single line text) can be added (to Advanced or Post Fields) which would allow for this? Possibly using the wp_insert function?