1. Instagram
Probably the most well known of the five, Instagram was initially bought by Facebook in April 2012 for $300M cash plus 23M Facebook Shares, equalling around $1B. The acquisition wasn’t made official until late August where by that time, Facebook shares value had dropped dramatically where Instagram was eventually acquired for around $750M. For a business less than two years old with hardly any revenue to its name, Instagram co-founders Kevin Systrom and Mike Krieger walked away with a lot more than they bargained for.

2. Wildfire
The most ironic acquisition was the $250M move Google made for Social Marketing Software Developer Wildfire. Knowing full well one of Wildfire’s most used features was its Facebook Competition option, Google saw this as a great way to improve its social stature as well as get a point in the Google vs Facebook war. Even more irony, Mark Zuckerberg’s sister, Arielle Zuckerberg worked as a project manager for Wildfire. Google didn’t just acquire Wildfire, they also acquired Mark Zuckerberg’s sister.

3. Yammer
Yammer is a social networking company for enterprises which was acquired by Microsoft in mid July 2012 for a whopping $1.2B. The acquisition was first rumoured to take place in late June but due to closing conditions, the deal didn’t go through until around a month later. Microsoft plans to incorporate Yammer into its new Office Suite, however details on this are still unknown.

4. Meebo
Another Google acquisition, Meebo the chat service, social toolbar and ad platform had been swimming around in Silicon Valley for around 7 years and was bought by Google for an estimated $100M in early June 2012. Meebo impressively secured $70M in four rounds of funding and over 100M total users per month, making it a great choice for Google to swoop in and secure Meebo’s fate.

5. Posterous
One of the most popular blogging sites alongside WordPress and Tumblr; Posterous was acquired by Twitter for an undisclosed amount. This is slightly different from the above acquisitions as Twitter is more interested in the people, not the product in this acqui-hire. Twitter has decided to keep Posterous as it is for now, with Co-Founder Sachin Agarwal leading the product management.Fun2BWith

Other acquisitions failing to make our top 5 list were; Sales Force acquiring Buddy Media for $689M, Amazon acquiring Kiva Systems for $775M and Facebook acquiring face.com for $100M.

Who do you think got the best deal?