To be honest, I'm not a big friend of gambling. But it is a way to earn Bitcoins so in order to make this list complete it needs to be mentioned here. However, I won't list any links to gambling sites here. It's fairly easy to research them if you are interested. And if you clicked on some of the above links you probably already came across some Bitcoin gambling sites.
Bitcointalk Forum Services Section is another starting point to look for job listings that are paid in Bitcoins. Some of the jobs are done easily within a short amount of time so it's a good way to earn Bitcoins quickly.
Jobs 4 Bitcoins on reddit has a focus on job listings for programmers. But again, it's not purely programming and it's definitely worthwile to browse through the different offers.
BitGigs is an online job board with many diverse job offers. The variety is reall amazing so go check it out.
Coinality has a different approach by not simply listing jobs where you can earn Bitcoins, but displaying them on a map. This comes in handy when you are interested in a local job somewhere near you. The number of listings could be higher but when it keeps growing it will become more interesting.
XBTFreelancer is another job board for gigs that are paid in Bitcoin. These jobs are mostly also software related. If you have programming or other IT related skills it is therefore probaly easiest for you to earn Bitcoins with your experise.
bitWAGE lets you find remote jobs that are paid in bitcoin. bitWAGE also offers a second, quite innovative service. They let you invoice your USA, EU, or UK employer or client in many currencies including bitcoin. This means that you can earn bitcoins from your regular job. Definitely something to try for real bitcoin enthusiasts.
Then of course, you can start your own Bitcoin related business and earn Bitcoins this way. Either as a fully fletched business of goods or services or you could run a website and place ads from CoinURL. If you want to start or already have a brick and mortar shop check out the earn Bitcoins downloads. The flyer shows you, how easy it is to integrate Bitcoins payments in your shop.
