There's a few low barrier ways to make money online. As with all these things, there are a large number of people doing them and only a few making any money. However, as long as you're only giving up time then it might be worth a crack:
Amazon Mechanical turk:
https://www.mturk.com
You basically get paid for doing small simple tasks. You can have a look around the site to get an idea. You're never going to make millions but some people quite enjoy it. Run by Amazon so very trustworthy
Mancx -
Mancx | The Knowledge Market
This is basically a paid Q&A website with an emphasis on quality. If you've done a degree then you'll probably be comfortable with the type of research required. Pay is better than a lot of sites because the quality required is higher. I think it's affiliated with LinkedIn so again, it's a legitimate place.
KGB answers -
General Knowledge Questions and Answers
Another paid Q&A site, quality is fairly low so the pay is too
Istockphoto -
Stock Photography: Search Royalty Free Images & Photos | iStockphoto.com
Have a digital camera? Pretty much everyone does. You can upload your photos to loads of these stock photo sites and people like designers pay to use them. Have a look at the most popular ones and see if you can copy them. Ideally you want photos of an attractive woman doing cliche office things (answer phone, typing etc) or middle aged man in suit doing similar stuff
Matched Betting - Google it
Most online gambling sites give away free credit when you sign up, usually £50 or so. The condition of this is that you need to gamble it x number of times before you can withdraw the free cash. The principle of matched betting is that you can use betting exchanges (where you effectively act as the book maker) to cycle the money and withdraw almost all of it. I'm simplifying this down but you can easily find articles on it so no need to go into too much detail
Article writing -
paid article writers per word - Freelancer.co.uk
One of the major tactics used by people in
SEO is to write articles and blog posts. You can get paid per word to write this stuff (usually low amounts of money). A recent google update has led to a decline in this work but you might want to look into it
Design work -
Logo Design, Web Design and Writing by the World's Best Creative Team | crowdSPRING /
Logo Design, Web Design and More. Design Done Differently | 99designs.com
If you can learn to do design then you can look at this. If you're not very good then this might get frustrating as it's payment on results
Skype prime - Download skype and look there
Have some expertise that other people would pay to learn about -
SEO, Design, marketing, photography etc? This is basically a marketplace where you set your rate per minute and people can call you on skype and pay for your time and expertise.
As with anything, if you want to make good money then you need to learn to do the things that other people can't/won't. Particularly online where you are competing with countries like India/China.