Sign up for a Google Adsense account to have Google place relevant PPC ads on your site. (The Yahoo Publisher Network also does the same thing.)
Create a Squidoo Lens and drive traffic to it. They share a percentage of the earnings with you that they get from the ads on your lens.
Sign up as a reviewer at ReviewMe and get paid to review products on our blog. You will earn $20 to $200 or more per review. It’s a similar situation at Pay Per Post, CreamAid (only get paid here if the company likes your review) and LoudLaunch.
If you’re good at cards you can play online poker but check your local laws first.
Sell ad space on you website or blog through Adbrite, Text Link Ads or Azoogleads.
You can add a job postings board on your website with Indeed. They base job postings on your visitors’ locations and the job types that you choose.
Refer people to Jellyfish. You get paid a percentage of the purchases they make on this shopping site.
Send traffic to sell your product or an affiliate’s with PPC ads, including Google Adwords, Yahoo Search Marketing, Microsoft AdCenter, BidVertiser (payout minimum of only $10).
. Sell prospective customer leads on InnerSell. This could be useful if you get an inquiry that you can’t use for your business.
Profit from website flipping - buy sites, spruce them up, build traffic, raise their PR and monthly income then sell them for a huge profit. Or just buy a site that runs on autopilot (these usually sell for 6-18 months of income). Keep it 1-2 years to earn back your money and then sell it to double your investment.
. Sign up at Vizu to have targeted polls added to your site. You get paid a CPM amount that you set and visitors don’t leave your page to answer the poll.
Sell household items you don’t need on eBay, as well as things you get cheap or free at garage sales or your grandma’s attic.
. Sell articles that you’ve written to Associated Content.

If you get 500,000+ page views a month then use Vibrant Media to have ads come up when the mouse is over a double-underlined word.
Predict the name of the next celebrity baby and register the domain now.
. Contact owners of websites with poor domain names and offer to find them a better domain. Say you’ll only ask for payment if they like the new name. Picky Domains charges $50 to do the same thing.
Use Clicksor to advertise in a variety of ways, or to be paid to place contextual ads on your site.
Sell your unused computer cycles (time when your computer is on but you aren’t using it) to companies who have big computing projects that they can’t complete with only their own resources.
Use LinkShare.com to place ads on your site. Shareasale and Clickbooth both have similar programs.
Get ‘hired’ to respond to customer inquiries on company websites.
Buy and sell domain names for a profit (including typo domains). Use Sedo, Afternic and DNForum.
Put a donation button on your site.
Sell your photos on sites like Big Stock Photo, Shutterstock and Fotolia.
Open a reseller account at a web hosting company and sell web hosting.
Write blog posts for company’s business blogs. If you’re not sure where to start, try Creative Reporter, which pays $10 per 1,000 page views of your post and provides posts for a bunch of blogs of all kinds.
Build a list of friends on MySpace to advertise your products to. Myspace users also love buying “resources” (templates, backgrounds, scripts, icons etc).