Well, there are 2 ways to look at it. The Adult industry is the largest and has the highest amount of revenue...period. Social Media owners of sites like myspace and facebook.. are billionaires..or worth a billion + So social media and Adult are probably the two most paying online "businesses" However as far as for the individual who won't be building a social media site or porn site I think affiliate marketing is right up there. The internet thrives on affiliate marketing! Affiliate marketing probably accoutns for 70% of all income earned online. When you search google, find a product, buy it... that was an affiliate sale (a large majority of the time) Think of how many times per day that is accomplished.
Incentive sites like treasuretrooper dot come and cashcrate dot com If you interested in setting up this type of site I can assist you just send me a PM.
someone said health but health supplement for google is usually pretty low sadly. selling niche supplements though has good markup usually.
As an article writer myself i get orders more on 1. weightloss/health 2. dating/relations 3. loans/finance 4. technology/gadgets So, these are the best in the industry right now. Start with a blog, adsense, cpa and it works with right marketing and seo for the site.
I've tried a couple of ways. If you can build a big site in a niche you don't mind spending time on then building your subscriber list is awesome. Because when you get a money making idea or product... you have the eyes and wallets already. You can make a couple of thousand just by sending a well thought out email and then watch your email and smile. Now for steady income, I think adsense is pretty great on tight niche small sites. Money just trickles in at a pretty dependable rate and you can keep building sites. Selling your own product is great once everything works. There is a lot of time invested in sales copy, product making, autoresponders and such but once it works, it's great. I personally find that health and fitness is great and electronics works awesome as well. Just my two cents.
Adsense and subsite expansion for generating backlinks do well for my customers. Don't even need to work through the community sites although adding those up can boost the backlinks if the community likes your site alot.
Do you mean one main site that makes the money through adsense with smaller niche sites pointing back to it slidetheweb?
There is a lot of good advise on this post, many general sectors that make money. But to really have an edge online you need to do something that someone else isn't. To fulfill a need or desire for someone which is in essence the basics of marketing anything. That is more general advise, but I agree with many of the responses on here. Check out the health and beauty, celebrity, adult genres for some of the top traffic and money makers. But in many cases people make a lot of money filling obscure needs, or filling several small genres or niches. It's not always best to go with the crowd, but it is definitely recommended to add a large amount of common entertainment sites to your portfolio.