Facebook is trialling a new feature, dubbed Highlight, which enables its users to pay to promote their posts on the social network, as the firm continues its active run-up to its IPO. The service would place a user’s post more prominently in their friends’ news feeds, with Facebook charging USD2 per post, though the social network says it is also trialling the feature at different rates and for free. The firm says it is trying to “gauge people’s interest in this method of sharing with their friends” as it explores additional revenue streams ahead of its highly-anticipated public offering. Facebook is also rolling out file-sharing to its group features, enabling users to upload files of up to 25MB, though it does not allow music or executable files. The feature is likely a product of Facebook’s undisclosed acquisition of private sharing service, Drop.io, in November 2010.

Highlight is the latest attempt by Facebook to diversify its revenue streams. The trials come just days after it launched its app store, enabling users to buy apps both on desktop and mobile, as it tries to lessen its reliance on advertising. To this end, it is also reported to be testing a version of its fledgling deals service that will enable users to redeem coupons at online retailers, as an extension of its Facebook Offers service for offline retailers. Facebook generated ­ USD3.7bn in 2011, according to its IPO filing, with ads accounting for 85% of that total, illustrating the need for more diverse streams.

Highlight represents another way for Facebook to bring in more money, and the service could prove an attractive proposition for both large and small brands, as well as individuals, aiming to give their message greater prominence. Facebook’s tool also bears a marked resemblance to the 'Spotlight' service rolled out by Tumblr earlier this month, which charges users USD1 to promote posts on the Tumblr Dashboard., hinting at an emerging trend for social networks and platforms to monetise users’ desire for promotion.

Facebook’s launches are indicative of a busy run-up to its IPO, seen by many analysts and investors as a defining moment in the recent tech and digital media boom. Reports claim that Facebook’s offering is already over-subscribed, with investors fighting for a look-in when it floats on the stock exchange. A Reuters report, citing a source familiar with Facebook’s listing, claims that emerging concerns about slowing growth, and Facebook’s revenue-generating performance in mobile, is not putting investors off. Facebook could even raise its price range if demand continues, which could net the firm more than the USD10.6bn it is targeting.