E-Books?

If this is in the wrong place then i apologize mods, it just seemed appropriate

I've been thinking of ways to gain extra revenue for my site footballmad.info, and i realised that e-books could be the way to go, but i was wondering how successful they are.

So, my question is: is it worth creating a couple of quality e-books? Have you guys ever tried this approach and had it pay off? If so, how did you do it?

Thanks.