Regional variation in English is something that many people celebrate: diversity and slightly different cultural nuances are healthy after all. Others find variation unsettling and long for uniformity. Luckily, Ian McMillan is in the former camp and he's written a piece for today's Guardian about the ways in which accent and dialect can be radically different over just a small distance.
One distinction he makes is the difference in pronunciation you can encounter of the word house, pronounced as it's spelt in some areas (with a sounded "h" and diphthong "ou") and pronounced "arse" just down the road. If you've ever read Jim Shelley's TV column in the Daily Mirror you'll probably be aware of the potential for humour of this house/arse interface when referring to Eastenders ("You're never comin' round my arse again!"), but McMillan's more interested in the Yorkshire/Derbyshire divide.
It's a good read and the comments posted online after it, show the divide between those who celebrate diversity and variation and those who lament it. Just take a look at George Ball's nasty dig about regional accent for an idea about how discussions about accent quickly turn into something much more personal.
Have a look too at this November 2009 BBC Magazine story about Collins Dictionary's attempts to trace the meanings and usage of old dialect terms, if you want to see a bit more about where some terms are derived from and how they developed.