Ways to make money online

I've seen a lot of talk about which type of marketing one should start out with. Personally, I think getting your hands in a bit of everything is a good strategy, but I thought I'd start with a list of a lot of the current ways of making money online with the pros and cons of how I see them.
Feel free to add your own comments, agree, or disagree.
1. Adsense. Pro -- easy to setup so that virtually anyone can do it, and it can apply to virtually any website with content. It requires little to no maintenance other than providing content.
Con -- usually doesn't pay too much per click (although exceptions exist), requires a lot of content to be used on a large scale, and better with really large sites with lots of traffic or several sites made on a very large scale. You can also be dropped if it's believed that your sites are spam. It's also not always a good idea to do Adsense with other types of marketing (like affiliate marketing or your own product), as your competition can direct traffic away from your site.
2. Affiliate Marketing. Pro -- easy to setup affiliate links, and affiliate products can be found in most niches. Payout can be anywhere from a couple of dollars to thousands of dollars per person who buys through your link. Usually it doesn't require too much maintenance. Can be profitable on smaller scales as well as larger scales. Very easy to do with mailing lists too.
Con -- Some affiliate programs are easier to get into than others, and some programs won't accept you unless you already have a good site that they approve of. Some programs require some basic maintenance now and then (although not all). It's easier for people to steal your affiliate commission in some programs (especially Clickbank, but not all are like this), and not everyone will always click on your affiliate link even if they are interested (although there are ways to encourage them to). You're also dependent on the merchant, who can change things any minute (although again, there are ways of making this less of an issue).
3. Your own tool/program Pro -- if it takes off, you can make a lot of money and have total control over it. You can have your own affiliate program and be in total control of marketing it. You can also have similar tools developed for different markets (online vs offline businesses -- remember that). A tool that fails in terms of online marketing still has a chance of being promoted to offline companies as well (which most likely will pay more). You can also add affiliate marketing into your program in some cases, as well as build a list.
Con -- unless you're a programmer, you'll often need a budget to hire one to make your program. Some can be very costly to develop (not all), and there's not always a guarantee that it will take off after your investment. You have to know your niche and marketing to be able to have an educated guess as to whether or not it will take off. New tools also sometimes require extra time for support, and you often have to either update them or face tough competition as times and needs change.
4. Your own guide Pro -- As long as you can write and know something about what you want to write about, this is fairly easy and cheap to do. If it fails, you mainly just waste your time (or a minimal budget) in most cases. It's much easier to update or modify than a program. You're in total control of your guide and can have your own affiliates. If it takes off, you can make a lot of money. It's very easy to add affiliate marketing into your own guide too and build a list.
Con -- No guarantee that your guide will take off, and it can be hard getting affiliates to promote it. It's also hard to have your guide stand out above others in some niches, and you do have to know something about your topic and have knowledge of something that others would want to know and pay for.
5. Your own skills (aka programming, design, etc.) Pro -- You already have what you need for the most part, and there often is a demand for almost any skill out there. Online it's fairly easy to advertise your skills and find people who might need you.
Con -- You have to prove that you're good at what you do, and you have to satisfy the needs of others -- even if their expectations might be vastly different than yours. It's harder to grow past a certain point, as there's only so much you can do. And it might be hard finding work from one week to the next depending on how well you market yourself. This probably requires the most work, as that's what you're being paid to do -- work.
6. Pay-per-leads Pro -- Often a higher payout per person than Adsense, and it's fairly easy to implement them on almost any website. They usually require very little maintenance once set up.
Con -- Many pay-per-leads are extremely picky about who they let in, and some require the visitors to do a lot more than just click a link (it might require them to fill out a survey, sign up for something, receive a phone call, etc.). It's also harder to do other marketing like affiliate marketing or have your own products on the same site, as you're having others sign up for possible competitors.
7. Buying/selling expired domains. Pro -- It's fairly easy to list sites for sale or to buy them. Some good expired domains can be bought fairly cheap.
Con -- You often need huge budgets to do this on a larger scale, and some of the better domains could cost you thousands to hundreds of thousands of dollars. You also have to be very patient for buyers to come about, and there's no guarantee that any will sell. You also have to really know your stuff and deal with a lot of competition for the better names.
8. Membership sites. Pro -- You often get money each month over and over again from the same subscribers. Can be a more stable income than some other methods, and there are a ton of great tools out there to help build a membership site.
Con -- You have to offer a ton of content and/or tools to entice subscribers to stay, and you also have to be constantly marketing it to get new subscribers. It can be a lot of work just to maintain enough goodies for people to stay, and it's not always easy launching one unless you really know you have something that people want and will pay monthly fees for.
9. Dropshipping. Pro -- You don't have to have any merchandise on you, nor do you have to pay for it ahead of time. It's easy to do things like this with Ebay and fairly easy to setup a website with a low budget.
Con -- You have to be sure that your dropshipping source is a good one and that your competition isn't too big already. To have a really good website, you'll need a budget (or be good at designing one) in order to make it look trustworthy and professional. Profit margins aren't always that big, and it isn't always easy getting people to buy from you instead of others with the exact same products.
I'm sure that there are a few other ways that I didn't list here, but these should be the main ones. Just because one has downfalls does not mean that you shouldn't try it.
Ideally, I think that the best ways are ones that either require very little maintenance on your part (so you can expand) or pay very well if they require maintenance.
The one thing that I think is often overlooked is with product creation. Not all products based online have to be marketed to online sites, marketers, etc. There are plenty of tools that you can find for free online that have similar features in tools that cost hundreds to thousands of dollars and are marketed to offline companies.
There are also a ton of different pros and cons that can vary depending on your niche and/or site. All of them require at least some work -- there really isn't an easy way out. Although some require less work and maintenance in the future than others.
If you're just interested in expanding, it's ideal to find ones that even if they require a lot of work initially, require very little maintenance later. This is how I plan a good portion of my online business and should work for others as well.

Article by Brian Koz Courtesy of ezinearticles