1. Go to the library or a bookstore. Pick a section, then pick a narrower subject of that section. Now, figure out how you could monetize and traffic you had on that subject.
2. Ask your family what they want for Christmas or their birthday. Say they ask for an ipod. Now, find the most specific keywords you can to cut down on competition, and use amazon affiliate links in your post.
3. Write down 10 items in your office, pick 3 and get all of the model specific keywords that you can. So, instead of 'printer', you could go for 'HP Photo Smart 9400 all in one'. Again, this lends itself best to amazon affiliates.
4. This is my personal favorite: pick one of your hobbies or interests. Now break it down into 5 smaller sections, and then break those down into 5 smaller sections. Working one of the smallest subcategories at a time, build a site to build a massive list.
5. Go through your monthly budget or spending, and find 3-5 things that you spent money on that you didn't need, only wanted. Things like DVD's, CD's, a new cell phone, whatever. Any item over $50, use amazon affiliates. Under $50, stick with adsense.
6. This is a weird one. Go through your college courses. Every class you took is an opportunity to make money. How? That's where you need to be creative. For Calculus, a $20 ebook that explains foundation concepts that you could sell. For history, be an amazon affiliate for box DVD sets on the civil war or world war 2. Im currently taking a class called 'mans dependence on the environment'; I made an ebook on 101 ways to cut your utilities and help the environment. Like I said, this method is weird and takes some creativity, but it works.
7. Jump on the bandwagon! If there's a product on clickbank, there's a market for it. Either build a list in that niche or promote your own product, just send people to a sales page doesn't convert very well (versus the other two options.
8. Look at google buzz or yahoo trends, and put up adsense pages as quickly as possible. This is best to do on a randomly named domain, so that you can cover different topics as they come up.
9. Articles online. Again, not all of these will lead to anything, but some will. Here's an example: there was an article online a few days ago about the new Halo game coming out. Now I could be wrong, but I'll bet there's a guide for that game on CB about a week after it comes out.
10. Commercials on TV. These are no brainers, someone is paying a ton of money to show that ad. See what you can do them them. For example, how many dog food commercials have you seen? I have a dog food cookbook that earns about $700 a month on my dog training site. There's all kinds of things that you can do.
11. Tv shows. Again, this won't work every time (and it takes some creativity) but you can actually get some good ideas just from watching TV. An example is the show Overhaulin. I watch it almost every day, and I started wondering how many people search for 'how to rebuild an engine' or some variation. The answer: more than enough. You think people rebuild a $4000 engine would spend $40 on a weel written guide? Of course. How about $97 on a video guide that showed them every step?
12. If you have kids, ask them what's cool at school. This could make you absurd amounts of easy money. There's a fad every 2 years or so, and parents literally wait to spend money on them (not judging, Im sure when my baby is older I'll do the same thing). Here's an idea how powerful this is: anyone in the States remember beanie babies? Enough said. The creator not owns the four seasons hotel in Manhattan, and 14 other luxury resorts. Best way to monetize? Depends on the fad, if there's no direct affiliate program, then amazon or adsense.
13. Think of 15 places you'd like to travel to. Do keyword research, and make as many keyword specific pages as you can. These are another good bet for adsense.