I wouldn't go for
that kind of affiliate marketing. If the things the affiliate program is selling are mainly e-books about affiliate programs, that isn't a very good sign. Actually, I'm sort of wary of affiliate programs that sell almost exclusively e-books of any kind, although some people seem to like Clickbank, which is sort of like that.
More mainstream affiliate programs are things like: those from bookstores (Amazon, Powell's), the eBay affiliate program, most of the stuff that goes through LinkSynergy (e.g. iTunes affiliate links), etc. There's scammy stuff that happens with sites targeting those too (there's a whole sub-culture of JS exploits trying to illicitly shove your affiliate cookies into people's browsers), but the programs themselves are above-board.
I can't speak to whether it can get you rich, but for the time I invest in it, I make decent beer money from some Amazon links, and they're pretty transparent about how the program's operated. I have a site mostly dedicated to other things, but where it was useful to mention a book, I mention it with an Amazon link, and now and then someone who clicks through buys stuff. There's a different approach, where you build a whole site around landing pages pointing to specific affiliate links, as opposed to using affiliate links to monetize an existing site, but I don't know much about the ins and outs of that one.