There's been a lot of speculation about numerous internet behemoths going public on the stock market, so all eyes were on LinkedIn's share ticker on Thursday as the firm hit the New York Stock Exchange.

And all eyes were soon rolling upwards as LinkedIn's share price doubled from $45 to $90.49 within four minutes of the opening bell, and had hit an all-time high (admittedly in one day of trading) of a whopping $115.09 per share by 11:48am.

No doubt those who stuck a wedge of cash in the business version of Facebook would have been patting themselves heartily on the back as fortunes were made - on a company that turned a profit of just $15m in 2010.

How LinkedIn performs today will be of interest; was day one nothing more than frenzy based on novelty, or do the financial whizz kids of Wall Street see something in LinkedIn that appeals to their monetary senses?

The firm's performance in the coming months could well be the reason that other giants of the social media world, such as Facebook, Twitter, Groupon and gaming firm Zynga, which owns the bizarrely popular Farmville, go public. Or not.

The smart money would suggest it'd be good to get some stock in these companies before the trading bell rings if they float based on LinkedIn's early rises. But others will see the money involved as further signs that we're in a second tech bubble.

One public offering is hardly a bubble in itself, but the money involved is amazing; LinkedIn's paltry $15m profit was its first in four years, while sites like Facebook are valued in the countless billions owing to huge numbers of loyal subscribers.

However, both rely primarily on the age-old cash cow of advertising for the majority of their revenues, alongside more capricious income streams such as Facebook's developer fees or Twitter streams in Google and Bing searches.

Irrespective of the financial unknowns, executives and shareholders in LinkedIn no doubt spent a pleasant night smoking cigars lit by $50 bills as their investments made them more money in one hour and 48 minutes than most will earn in a year.

As technology continues to advance society faster and faster it's almost inevitable that cash will become a concept that future generations look back on with incredulity: "You had to carry paper and coins with you to pay for stuff?"

The latest move has come from Vodafone. The operator is to trial a system that lets customers in London pay for any of the hundreds of taxis it is putting the streets painted with Union flags (see below), simply by texting the number of the cab to Vodafone which will charge the fare to their bill.

This means any late night revellers, businessmen getting soaked in the rain on the way to important meetings, or tourists who've forgotten to go the cashpoint will always be able to grab a cab as long as their phone is in their pocket (and they're on Vodafone).

Customers wishing to sign up for the pay-by-mobile taxi service need to call 0845 680 3409 to set up the free service. They then text the word 'taxi', the taxi's number and the amount they want to pay to 80010. Not a penny in sight.

The cabs will also contain chargers for devices including BlackBerrys and iPhones, so all mobile users can ensure they have plenty of juice for their journey.

"Now with our fantastic fleet of Union Jack cabs and their onboard chargers which anyone can use, all Londoners will be able to see our continuing commitment to the capital," said Vodafone chief executive Guy Lawrence.

If this catches on you'd expect to see other network operators rolling out similar schemes, something that taxi drivers and forgetful travellers must be looking forward to immensely.

And with near-field communication technology rapidly advancing, it wouldn't be a push to see the major operators wrap these capabilities into this kind of service before too long.

One of the Vodafone branded taxis set to hit the streets of London.

It's official - social networking is the UK's favourite online activity.

This is hardly a surprise, in fact to many it'll be more of a surprise that it's only been announced now, but figures from web monitoring firm Experian Hitwise found that sites like Facebook accounted for 12.46 per cent of all internet traffic in January.

This surpasses the 12.18 per cent of traffic to entertainment sites in the same month, the first time the two categories have traded positions (see image below).

The figures are all the more impressive because it underlines the huge growth social networking sites have seen in the past few years, with visits rising from eight per cent of all hits in March 2008 to over 2.4 billion visits in January 2011.

Facebook, unsurprisingly, was the dominant social network in the UK, claiming 56 per cent of all hits. However, users rarely went to just one social network, Experian said, while the average session for a user was 22 minutes.

While this is great news for Facebook, Twitter et al, businesses are failing to take advantage of this growth, it seems, as just 16 per cent of all referral links from social networks are sent to transactional web sites.

As it is, search engines still dominate in this space, with 33 per cent of all searches leading to such web sites and research director at Experian Hitwise, Robin Goad, said that firms needed to embrace the new opportunities on offer.

"Transactional web sites - those selling goods or services such as travel or insurance online - still rely primarily on search for their traffic and therefore sales," he said.

"Successful transactional web sites will be those that learn to harness the power of social networks, driving traffic through to their own websites."

Businesses can't claim they're not provided for either - on Monday IBM announced a new Smarter Commerce initiative that aims to give firms the ability to generate more revenue and improve feedback based on interactions with social sites.

With UK internet users spending more time on these web sites than anything else, businesses can't afford to ignore the potential on offer any longer.

Source: Experian Hitwise