http://www.techwench.com/link-building-when-link-buildings-hard/

Link building isn’t easy everywhere. If you have some great, socially friendly website like Digg or Facebook, the links come in in droves. However, we don’t all have that luxury. Link building in the less social friendly niches becomes more of an arduous, detailed campaign of trial and tribulation the further south in friendliness you go. So, for the link builder, it takes extra skill and wherewithal to dig links out of the internet’s infrastructure. But it’s possible. And really, it’s easier than you think.