1. Check out this sexy/scary/horribly tasteless video. Just complete this survey or install this viewer app (which is really a virus/malware) first.
This scam plays on our curiosities. The bait is often usually something outlandish or morbid such as a "Shocking" video. An alarming number of people re-post these scam links before they even verify their content. This helps the scam go viral and spread worldwide in a matter of hours. The more outrageous the topic, the quicker the scam link is likely to spread.
2. Facebook is going to start charging, pay your fee here.
This scam has many variations but the premise is fairly simple. Scammers tell victims that Facebook is now going to start charging users for their accounts. The scammers tell users that if they don't pay then their account (and all their funny cat videos that they've posted over the years) will be deleted.
3. The Dislike button, who's viewing my profile, and other fake Facebook feature scams
For some reason the big FB doesn't want any negativity on their site. We get new features like the "timeline" and "ticker" thrust upon us every other week, but no dislike button. I believe in all honesty that if the next presidential hopeful said "If I'm elected, I will mandate that Facebook add a dislike button" they would probably win by a landslide.
4. My friend got a free and I can too by visiting/installing
We all love free stuff, and if we think our friend just got a free iPad because he posted that he did on his wall, then who are we not to believe him. We better hurry and go get ours while the getting is good.
Your friend likely installed a bogus app that takes advantage of the "allow friends to post to my wall" feature on Facebook. The app that he installed posted the scam message on his wall and the wall of all his friends making it look as if it was from him. He probably has no idea it even happened.
5. I'm your best friend and I'm stranded in and have lost my wallet and/or passport. Could you please wire me some money?
When hackers break into a facebook account they will often try and impersonate the person who's account they compromised and try and bilk money out of their friends. Your close friends may think that you are in trouble and may actually fall for this scam before you can contact them to let them know it's bogus.