my work mate at the time was in the same boat, he was also in negative equity and just couldnt move as his house was worth more than 20K less than his mortgage, I was still at home in my mums houses and would often " sub him " so he could have a beer or 2 on a friday
I would hate for them times to return, as back then we were taking 50 K mortgages, now we are talking 250 K, they just wouldnt survive