Moderators can post a thread in mod forums to request a ban for someone and from there a higher staff member will look into it (Sal, Lowfyr) and decide what to do with the request.
As for the users to be-able to suggest others to get banned,
no. There is a reason why only moderators can post ban requests.

I don't see why normal people should be able to do something like that, couple flames aren't just enough to ban someone + I don't have to ban anyone based on personal issues. lol