I want to know whether I can allow users to create their own categories of their choice and whether this will be good or whether it will lead to spam? and also tell me whether I can allow users to submit their sites to multiple categories?
you should not allow users to add categories as most of user will create same category for multiple time and it will be problematic for you. well you can allow users to submit their sites to multiple time if your dir. paid and if you are going for free dir. then its not a good idea.
I like the idea. I submit dozens of sites. Many times I can't find appropriate categories for some of the sites. You will get spam - no matter how many categories you have. I am against multiple category submissions... just increases the work for the reviewer.
No it will not be a problem for me if I allow multiple categories In my words it is multiple keywords
Your questions are confusing... are you asking us permission to do something? because everything is possible with the right code...