Trendhunter.com We saw Jeremy Gutsche, the creator of trendhunter.com, speak at IIDEX a year or two ago. I've been following the site ever since..and by following I mean wasting endless hours jumping from trend to related trend.
thecoolhunter.net is now apparently trying to get into the real business side of trendhunting by offering services to companies to help make them 'cool'...I don't know
Google Insights throw in some related words to whatever you think might be a trend and Google Insights spits out some hard data on how often people have searched those terms! It gives you a pretty accurate look at the slope of the 'trend' over time, albeit only on the internet and through google. While not exactly a trendhunting website, it is definitely a useful tool for us for researching and confirming trends.