Amazon Affiliate Program - Easily create a store or shopping section on your site instead of sending your visitors to Amazon. Amazon handles the shopping cart and fulfillment.
Amazon Seller - Sell your stuff on Amazon
Associated Content - If you write a story, how-to, rant, etc. you can submit it to them and they will pay you $3-$20 per article if they like it
Azoogleads - Another ad program. They do have some decent companies lined up as advertisers. You provide space, they'll provide an ad.
BidVertiser - PPC (pay per click) program with a low $10 payout amount.
Build a Niche Store - This is a simple store / website development platform which enables you to create content based sites that generate income through the eBay affiliate programs. Pretty darn simple.
Blog - Start a blog and consistently write excellent content. With good ad placement, you may make some money. I detail my process here: Simply Said, How to Blog.
Business Opportunities Blog - I am adding this because I am a subscriber to their site and I see ideas everyday that could result in making money. A lot of the ideas pertain to online businesses. If you are an aspiring entrepreneur, it's a good reference.
Cafepress - You provide a design, they'll toss it on a T-Shirt, Hat, etc. No upfront costs. Get a free online shop and promote your products on your website.
Chitika - Their eMiniMalls service has shown great results for many Bloggers and site owners. You choose a keyword and they show relevant products on your site using a pretty unique interface.
Clickbank - Another Affiliate Program site with 10,000+ products to advertise.
ClicknWork - Get paid $5-$150 per hour for basically doing freelance work on a per-assignment basis. You have to pass a pretty tough test to get in.
Clicksor - These are the guys that generate contextual ads on sites that show up when you hover over a double-underlined word.
Commission Junction - If you have a site, you can join Commission Junction. Once enrolled for free, you can choose companies whose ads are pertinent to your site. Companies have the ultimate say on working with you. There are easily over 1,000 companies to choose from here.
CreamAid - For blogs only, advertisers provide you with a topic and you write about it on your site. To do this, you have to install a flash widget into your blog post. The more people you bring into the conversation through the widget, the more you get paid. It's difficult to explain.
eefoof - Think of it as YouTube + Flickr + Music. You add original content and they pay you based on the visitors you attract.
Ether - If you are an expert on something, Ether provides a way for people to pay you to talk about it in a one-on-one setting. If you want to charge $250/hr, that's fine. You have to do all the advertising so you should have a blog or site already established.
eBay- Come on, you know what this is. Gather your junk and sell it!
eBay Stores - If you have a real store and want to sell your stuff online, this is a decent option to get you started.
ELance - Name gives it away. Programmers, Codes, Web Designers, Writers, Editors, can look for freelance opportunities.
Feedvertising - This is an arm of Text Link Ads and is currently only good for Wordpress 2.0 Users. This does me no good currently, but as you can guess, they place ads in your feed(s).
Feedburner / Google - Not only are they the best place to house your feeds, they will also add ads to your feed and website. You get paid per impression and if you implement Google Adsense to your feed, you are paid per click.
Google Adsense - Come on, you don't need an explanation; these ads are all over the place. Google displays relevant ads based on your site's content
Google Adwords - Create simple text ads and choose keywords that determine when they are displayed. This is where the Adsense Content comes from. You do not need a site for this.
H3.com - Get paid to fill jobs. Commissions range from $50-$5,000. It all depends on how tough the job is to fill and how desperate the hiring company is. This is another one that's tough to explain.
Indeed.com - Add their job board to your site. They then post jobs based on the geographic location of visitors and the position types you pre-select. I tried it and I they continually report that I sent 0 visitors and I know that's not right. Nevertheless, I may have an isolated problem so they make the list.
InnerSell - If you have a customer that wants to buy something you cannot sell, you can sell the lead here.
Jellyfish - This is a shopping site that pays you a percentage of the purchases made by people you refer. They are not part of a wider affiliate program so you do it direct.
Jigsaw - It's a pretty flaky model but if you have a Rolodex full of good contacts, you can sell them here. I can't make sense of it but it looks like you get $0.10 per profile.
KarmaOne - They are basically a recruiting website. If you fill one of their jobs by finding a good candidate, you'll get paid anywhere from $50-$12,000. It all depends on how desperate the hiring company is.
LinkShare.com - If you have a site, you can join Linkshare. Once enrolled for free, you can choose companies whose ads are pertinent to your site. Companies have the ultimate say on working with you. Like Commission Junction, there are a ton of companies waiting to evaluate your site.
Microsoft Adcenter - Bid on keywords and Microsoft places your created ads then they are searched for. This is similar to Google Adwords. You do not need a site for this.
Overstock.com - Sell your stuff on Overstock.com
Pageflakes - This is a company that developed a user-defined Ajax homepage to show feeds, flickr photos, and a ton of other things. Think of it as a replacement for your Google Homepage. Anyway - they'll pay you $1 per referral that you send over. They are not part of a wider affiliate program so you do it direct. This one is pretty simple.
Pay Per Post - I don't agree with this model entirely but they have advertisers that will pay you to write about their products on your blog.
Pheedo - If you have an RSS feed, run it through Pheedo. Like Feedburner, they can include ads into your feed and if you really become large, advertisers will pay a premium for you to show their ads.
Shareasale.com - I've never really worked with them but I do have an account. They are similar to Commission Junction and Linkshare however they seem to have lower tiered companies with advertising offers.
Shoemoney - This is a blog that can teach you a ton on making money online. I've spent hours reading his old stuff.
Software Judge - They will pay you up to $50 to review software.
Text Link Ads - I have never made a dime here but I know people that have. You can earn by sending advertisers to them or by selling spots on your site. You must have a real site or blog to do this - nothing on a shared domain (i.e. /blogspot).
Vibrant Media - Don't bother unless your site has 500,000 page views of text based content a month. If you have that readership, these are the guys that display bubble box ads to underlined words on your site.
West Work At Home Agent- Not entirely online but this is worth a mention because it's won awards and is very legitimate. If you are an at-home Mom or free-lancer without work, you should check this out.
Yahoo! Merchant Solutions - This is a pretty simple and cheap way to create an online store.