Here's an article on the topic of Zakaat not being given to good causes besides the eight categories.
The eight categories are not listed in the article, rather they are mentioned in the Aayah, and they are:
(i) the poor; (ii) the destitute; (iii) those employed to collect the Zakaat; (iv) those whose hearts are to be drawn closer; (v) for the freeing of slaves; (vi) those who have incurred debt; (vii) in Allaah's cause (fee sabeelillaah); (viii) the stranded travellers.