At one time when Rown, the owner of Second Centaury, had the time and energy he maintained the best clearing-house website for all things centaur. These days the site is seldom touched and exists to house what was archived in the past. There is plenty of good centaur related information here including fiction, images and links.
Be warned that, if you are a liberal thinking (left leaning anyone?) gay man such as myself, Rown's politics and yours will collide. But, fortunately if you love centaurs, there is plenty of common ground to meet on.