I am not sure who is your target market. It doesn't mentions anywhere what is the purpose of creating a login, either.

However, I have a suggestion which might make it appeal to a broader audience. When a user creates a login, you can provide a list of celebrities of each category. The user can pick the ones he/she wants to read the tweets from for each category. Maybe adding an option of receiving daily email/rss feed be useful. Also, being able to add all the checked celebrities into the twitter account be also useful.