I used Google Adsense for a while which was very easy and classier looking than banner ads. phBB is the standard forum software (I think), and it is freeware, along with many things you might want. Do you know HTML, perl, or PHP?
I don't know any html, though I have a book on it in storage, and there's always the library. I was planning on starting with a WYSIWYG editor, and then optimize it later. I'm currently looking for a decent editor, and have dowloaded a couple I'm going try tonight/tomorrow. Someone on another forum has offered to hook me up with some free webhosting, when I'm ready for it.
ETA: you referred to google adsense in the past tense. Did you dump it for some reason and switch to another method, or were you just referring to when your website was still in operation?