I make quite a lot of money selling ebooks. You can either setup your own website selling them or sell them on sites like eBay, Tradebit etc.
Find yourself either a PLR (Private Label Rights) or MRR (Master Resell Rights) package and make sure the products aren't really old.
You can learn a lot by reading some of these ebooks about Blogging, Article Marketing, Affiliate Marketing and Getting Traffic.
Checkout this package of resell rights products (I think there's like 100 products plus bonuses).
Download all the ebooks and then put them up on sites like eBay, Tradebit, PayLoadz etc.
Also look into Niche Marketing. This is when you sell to a particular group of people. So for example you could sell ebooks about Cooking to people interested in cooking.
You can get a similar package of resell rights products targeting Niche markets on the same site...
Whatever you do, stick at it. Don't just give up because it seems hard work. If you keep at it you will eventually start making good money!
Hope this helps :)