I think it's okay as long as you don't go crazy with flashing or audio type banners. Just keep it simple and low key. Google TEXT ads (or something similar) is what I would use for something like this.
For professional sites, definitely text ads such as Adsense and the alike. It is best if the text links are targeted. It makes it look much more professional. Graphical 468x60 banner ads may not be appropraite. Depending on your site design & layout a rich media (flash) or regular (.jpg, .gif, .bmp) banner may be okay on a content page...breaking the text. I will still keep those targeted as well. e.g. If you do resume writing then a large rectangle (monster.com) breaking the text on a content page would be appropriate.