Well, generally anything beyond basic editing and effects built into the editor is generally a professional level kind of thing. The only free effects program I can think of is WAX (
http://www.debugmode.com/wax/), but its Windows. I'm sure there has to be something out there for Mac, but Google is your friend. And if you're a student, high school or college, you can always get an academic price. And even with these effects programs, many the effects you see are from expensive plugins for the programs. The way I generally see it is there are free ways including doing them yourself (e.g. lots of images and keyframing) or paying to make it easier.
Insert clever text/image here.