Passive Income -- Where to Begin?

So recently I have been doing a lot of research on how to develop some sources of passive income. I used to think real estate was a good way of doing that (via home appreciation and rent), but there are so many stories of failure and I am beginning to doubt my ability to take the gamble with rental property (I actually think I might be able to be more successful with online poker). I am continuously thinking on how to get greater interest on my savings (since interest on your money is in effect passive income) but I am also considering to think about other possible sources.One site I came across suggests using your talents to develop a product or website that people would want to use. Well I am perfectly capable of writing software (and better at managing other people writing software and I know how to outsource well) so I am still thinking of how a site or application I can come up with and build. So far I haven't had much luck thinking of anything good, but I am keeping it in the back of my mind should something come up (which is often how I come up with my good ideas).Another idea I keep coming across is drop shipping--setup a website, find a drop shipper and then take orders via your site and keep the profits. Sounds simple right? Well I found it difficult to find a good site to order baby presents on (at least when I was looking to send some baby shower gifts in the mail) and that meant a good opportunity. Especially if you could gift wrap it nicely--of course that defeats the drop shipping aspect. There are a few sites that sell baby items, but I still think I could do it better. Of course, though, there aren't very good sites that merchandise these things. So then I started thinking maybe I could leverage Amazon's associate program and build a site that puts together items from Amazon and then let them handle all the fulfillment. This could be a possibility, although I don't think the margins are as good as going through the wholesaler yourself since Amazon takes a cut (but it could be a way to supplement inventory with things like books at lower prices). This weekend is the Seattle Gift Show, so I am going to drop in there to see if there are any good wholesalers or drop shippers I may be able to leverage (although last time we were there they said that less retailers come because they can accomplish a lot more of their business online). This still may be an option but needs a bit more research.So what else can I do to get passive income? I am not sure yet. Eventually I plan to redesign this site, organize the useful content and then place some ads on different sections. My main objective is get write enough content that people will enjoy coming to the site and hopefully learn a thing or two :)