But few ever paid twice for Friends Reunited.
Once you'd handed over your fiver, shared a few reminiscent emails with Steve from the school football team, made an awkward pass at a teenage crush, and worked out that Dave from 3C was still the pillock he was 15 years ago, there was no incentive to go back. No status updates, no applications, none of the things that allowed Facebook to come along and steal Friends Reunited's dinner money a few short years later.
Friends Reunited eventually dropped the fee in 2008, but by then all life had been sucked out of the site. ITV sold it last year for a reported 25 million barely a fifth of what it had paid for it.
Dec Alpha
Alpha was a revolutionary CPU architecture. Designed by DEC and launched in 1992, it was intended as a workstation and server platform that would remain stable for decades, through successive generations.
Accordingly, even though a fully loaded server at the time might have had no more than 4MB of RAM,
Alpha was implemented as a fully 64-bit architecture capable of addressing 16 million gigabytes of memory.
In order for Alpha to achieve its intended long life, DEC realised that performance would need to scale up enormously over time. Alpha was therefore equipped with an extremely simple instruction set, and lacked some of the sophisticated features found on modern processors, so that massively increased clock frequencies and any number of additional cores could easily be implemented in the future.
On paper, Alpha was brilliant, and it got off to a good start: Unix and VMS distributions were ported to run on Alpha chips, and Microsoft published Windows NT for the Alpha architecture.
Unfortunately, although the product was sound, the strategy wasn't. Almost as soon as Alpha processors appeared, businesses began to move away from workstations and multi-user servers in favour of increasingly cheap and capable Windows PCs.
Microsoft shifted its focus to this market and began to phase out support for Alpha, leaving the platform and its manufacturer to serve a shrinking niche market. DEC faltered, and ended up being bought by Compaq, which was in turn acquired by HP, which halted development of Alpha processors in 2004.
Sun Microsystems
Sun's early sales success was partially responsible for its downfall. It sold oodles of its flexible systems to startups and web firms during the boom of the 1990s, leaving a glut of second-hand equipment in the market when the bust ruined everyone's fun.
Sun also continued to focus on systems based on its own Sparc architecture while x86 was taking off, leaving it trailing behind in the enterprise space.
Despite the ensuing sales troubles, Sun managed to stay innovative, buying and open-sourcing the productivity suite that became known as OpenOffice, creating Java and even offering utility computing systems a year before Amazon unveiled its own cloud product.
None of that could hold off the inevitable, however, and Sun's value slid to $3 billion in 2008. A year later, after shunning IBM's offer, Sun was bought by Oracle, leading many to speculate that the classic tech firm may be dismantled for parts.
Think of what Sun has created or backed: Sparc, Java, Solaris and OpenOffice. The latter still exists, but after disputes with Oracle, key developers forked it off to create LibreOffice now the default productivity suite for Ubuntu. And Oracle has already started using its ownership of Java to start hassling Google over Android. In other words, two of Sun's key open technologies have already been killed off or are being used as a blunt object to smack rivals. That isn't much of a legacy for such an innovative firm.
Apple: The comeback king
If any of the surviving companies in our top ten are short on belief that they can still turn it around, they should look no further than Apple.
The company has gone from the brink of bankruptcy to the biggest tech company in the world, thanks to the success of the iPod, iPhone and iPad.
Apple came perilously close to going out of business. After Steve Jobs was ousted in 1985, the firm stumbled through a series of missteps, and its more expensive machines couldn't keep up with cheaper PCs and clones.
In 1997, however, Steve Jobs strolled onto the stage at MacWorld Expo as interim CEO, with $150 million in backing from Microsoft. Apple fans in attendance apparently booed the move, but Jobs quickly set about rebuilding the company he helped found.
While Apple has never recovered its market share on the desktop, high margins and a series of market-defining devices have seen it top the market value of its saviour Microsoft. It's a Cinderella story any struggling tech firm would hope to emulate, although it's left many worrying each and every time Steve Jobs takes medical leave.
