Five days ago we brought you the story of Constance McMillen, a Mississippi student who was being denied entrance to her prom because she wanted to bring her girlfriend.

The news went viral online quickly and a Facebook campaign started, getting 40,000 fans in 12 hours. Well that total is now up to over a third of a million fans and Constance has been doing the rounds on the major news networks to make her case.

It's a great example of how the internet is bringing news to the fore in a way that would have been impossible 20 years ago, and this is something which is causing great concern to companies.

We're seeing increasing numbers of instances of customers taking their complaint online and seeing it go viral. A good example is the United Breaks Guitars song.

Some backstory: A band were flying to a gig and saw United loading crew throwing their guitars into the hold. When they arrived sure enough one of the guitars was broken and the owner got brushed off by three staff when he complained and nine months later he still had not received compensation.

The band then took an unusual revenge. They wrote a song about the experience and stuck it on YouTube, where it has had more than eight million hits. United caved in and apologised but the damage had been done.

Imagine you're a chairman or marketing director spending millions each year on marketing your company's good name. Then you log on to YouTube and see that. It would put rather a crimp in your day.

However, this doesn't always work, and this seems to be the case for McMillen. Her beef is with Itawamba County Agricultural High School, which is relatively immune to such attacks. The school is sitting it out, holding to its position and ignoring the online storm.

The power of viral internet memes is great indeed, but only in certain circumstances.