It's no secret that Facebook is a big business and everybody wants to latch onboard and reap the benefits. Pretty much every business out there today wants to get more Facebook fans and likes. The only exceptions seem to be technically unsophisticated local businesses that still use faxes and possibly telegrams and don't care less about internet culture.
Interactive Design Agencies
A lot of creative web agencies are buying Facebook likes on behalf of their clients and using various services to give their clients' social pages a little kick in the pants. This seems like a worthwhile add-on and upsell for many web development firms, so they can get back to the fun creative design faster, which is what most of them are really passionate about besides artisanal beers and those really tight pants.
Many musicians and artists buy Facebook likes to promote their band online and also in the real world. In an age where physical distribution isn't necessary, many bands try and run their own business and setup their own online store accounts and book their own gigs. Venue managers then get swamped with bands who want to book with them. It's hard for them quickly filter through and decide which bands are cool and which aren't without spending a lot of time researching them and listening to them and feeling out how popular they actually are, so oftentimes a lot of these gigs get booked by who has the most Facebook likes. It turns into a competition of sorts. This is also a segment that really focuses on the external trappings of popularity, so like counts and follower counts are important here.
Many small businesses buy Facebook likes. A big part of the reason many of them do so is for the sake of appearances. When their local competitor has more Facebook likes, it doesn't look good to be stuck with a few dozen likes. Buying likes can certainly improve conversion rates and help give any page a boost, but it's not the only thing that a small business should be doing to grow their page.
Politicians and Governments
In a widely reported news story, the State Department spent a whole truckload of cash on getting more Facebook likes. Spending more money on good web design to make sure people are served is one thing, but a lot of taxpayers were upset about this. There have also been some interesting news stories about Mitt Romney and even Obama allegedly buying likes and followers, but who knows what happened there. Still, it's likely that society's biggest drama queens probably do have to pay people to follow them.