So what is a logical brand extension and when is it likely to cause more damage than good?
You only need to think of some iconic films like 'Rocky' and then think of the sequels.
By the time you get to 'Rocky 23', the idea has been exhausted, the story line thin and the impact watered down. The same applies to brand extensions.
Great brands have always been created from a single minded idea -- a gap in the market, an aspiration to be different and ultimately a desire to lead the pack, not follow.
When Absolut Vodka launched extensions to its brand with flavoured vodka products, it managed the leap by sticking by its core values.
They have always defined themselves by the purity of their product -- from its spirit and marketing through to its clean, simple packaging.
The extension works because the new product adheres to that original value of purity -- albeit with a touch of Citron.
Arguably the greatest master of brand extensions is Google, which has built itself into one of the world's biggest brands by continually developing new offerings.
Google's core values have always been finding an opening in the world of technology and filling it.
This has allowed them to both carry on as the worlds most successful search engine while simultaneously developing everything from email services, to crossing over into the off-line world and delivering mobile phone handsets.
In order to do this they have had to take account of the following elements -- Relevance, Recognition, Credibility and Transfer.
Any brands looking to expand must first ensure that they understand their primary audience and then develop products and services that cater to their needs.
Beyond this they must insure that their brand characteristics match the new products.
For example a young, bold brand would struggle to present itself as able to deliver in the formal world of business services. The mismatch of original and new product would cause an inconsistent brand.
Brand extensions are also affected by the size of the original brand. When Nike launches a new product line, the strength of its brands means that if a new product fails it won't affect the bigger brand image.
Brands can also use their existing position to enhance the launch of new product ranges through negotiating extra shelf space and encouraging vendors to backup any advertising campaigns.
The economy is pushing brands to think more carefully about their product lines. They have the option to either launch more lines in an effort to maintain their market share or to cut down on extensions that don't work.
The news has consequently reported a flurry of both. With some companies slimming down such as PepsiCo's move away from juice type drinks (dropping product lines Tropicana Spirit and PJ Smoothies) and Wrigleys chewing gum, aiming to get back to basics with fewer products.
While others are using their existing brand to support new activity such as The Guardian newspaper group planning to get more of its online revenue through online dating and travel strands.
All brands whether they are a vodka product or a search engine and their extensions, are fighting for the same shelf space and consumer attention.
But every extension dilutes the core values of what their brands originally set out to achieve a little bit more.
So brand managers need to remember that unless their extensions remain true to the original core theme, far from extending the brand's long term growth they may well find it having the opposite effect.
Glenn Tutssel, executive creative director, The Brand Union.