While it may be tempting to start blogs and sites that appeal to lots of top categories, this strategy may spread you out too thin and prevent you from ever truly optimizing any of these channels. Start with one niche that you are the most knowledgeable about, establish yourself as an expert and then expand out from there. Only then start working out other areas.
If you are a professional photographer or have a real flair for photography, then selling your images on other sites could be an idea. This could be done alongside your own photography site, as it is a good way to help get your work viewed by a wider audience. There are numerous stock image websites to contribute to, but choosing a popular high-end site like Shutterstock should ensure your photographs make you some money.
Data entry encompasses different job titles, but they all usually include inputting alphabetic, numeric, or symbolic data into a company's system from written or audio files using a keyboard and computer. Most legitimate companies hiring for this type of work hire people as independent contractors and not full-time employees. Data entry jobs are frequently the bait in work-from-home scams, so be sure to examine opportunities carefully. Never pay for kits or software.
Mechanical Turk is Amazon's take on micro-jobs. These are small miniscule-jobs that you can do for other people, which they call HITs, or Human Intelligence Tasks. These are super simple tasks that anyone can do. Some examples are listing off some URLs with certain kinds of images for one cent, or recording a few phrases with a microphone for 6 cents.
This has become a popular business model for online entrepreneurs over the past several years, and will probably just continue to grow in popularity. The best thing about selling online courses is that once you do the up-front work in creating the course and setting up your marketing strategy, you can get paid over and over again for work you do once.