This year was certainly significant in the world of online social media. Facebook surpassed 350 million users -- more than the U.S. population -- and Twitter's short blogging service skyrocketed in popularity, led by celebs, tech lovers and top companies.
Here's a look back at 2009's biggest events in which social media played a major role.
10. "Word of Web." As people spent more time chatting online and in public spaces like Twitter, buzz surrounding product and entertainment releases became instantly quantifiable. The elusive word-of-mouth promotion could now be measured, and "word of Web" became that new currency. (Marketers love to use the word "viral.")
The movie "District 9" played the game rather well. The low-budget sci-fi flick started the buzz train early with cryptic alien decals around major cities before its release. Despite relatively low advertising spending, the movie did extremely well. The fact that it was actually a good film certainly didn't hurt.
9. Whopper Sacrifice. Facebook was quick to kill this marketing ploy, but Burger King had a picnic with this one. The Whopper Sacrifice game asked Facebook users to delete 10 friends in exchange for a free burger. In just a couple of weeks, 233,906 friends were dropped like a bad habit.
It proved to be a hilariously successful way to promote a brand that seemed to get only more controversial and creepy over the course of the year.
8. Google Wave. In Gmail-like fashion, the exclusive nature of Google's newest product (people vied for a limited number of invitations from friends) made it the must-have free service of 2009. Of course, once people finally got hold of Wave, their lust died down.
The interface is still pretty confusing, and the team continues to struggle with growing pains in its mission to create a stable collaboration platform. However, it packs some intriguing technologies that could very well transform journalism in addition to a number of industries. But right now, e-mail replacement it is not.