Board Thread:Oblivion/@comment-24.182.147.198-20140306210804/@comment-14027812-20140312214334

See this page. I can't remember anything about the Fighters Guild, but the generic magic students and wizards outside the Arcane University can be asked to follow you after you complete the Mages Guild questline. Additionally, the Dark Brotherhood and the Knights of the Nine also offer followers (The Dark Brotherhood Murderer and the Knight of the Nine, respectively) after finishing their questlines. Hope this helps.