I'm tempted to purchase a short single word domain for £xx,xxx which 99% of the population would consider to be a generic term. (The word is actually a trademark owned by Kawasaki.) As far as I can tell, in the US such 'genericized' trademarks formally lose their legal protection after a period of time e.g. Escalator, Heroin, Yo-Yo. But in the UK, I don't think this status exists - however, a quick google search on the term 'hoover' shows that Dyson is using the term in its Adwords campaign...so maybe there is no problem. I appreciate this is probably one for the lawyers to sort out - but I'd be interested to hear your views.