If you're a photographer and would like to make some money on the side, selling your photos online is the way to go. I recently discovered that you could do this through 500px.
500px have their own market where you can sell your pictures as prints or HD downloads. You can make $2 per HD download and 70% of the net proceeds from prints. All images have to be uploaded in JPG, must be of size of 3600px along the longest side, have no watermarks and must be in a format of either 3:2, 2:3 or 1:1.
There is a minimum payout of $100 and you can either be paid by cheque or PayPal.
Even though 500px isn't as popular as Flickr, the quality of pictures is a lot higher. The design of the site is also fantastic and makes viewing images a real pleasure.
This is a great way for anyone who takes pictures to make money out of them. Obviously you won't make much at first but as you get more popular and build a portfolio you will start to make money. Just don't expect it to take over your full time job.
At the same time you can buy prints yourself of others pictures. Some of the pictures on the site are truly astonishing.