This is a good, free site too: http://www.calorie-count.com/

I kind of do things backwards; I like to figure out how much I want to weigh in the end and then eat that many calories now (the maintenance/goal amount http://www.calorie-count.com/calories/calories-goal.php :-) on the theory that I'm obviously eating more than that or I'd weight that amount now? So, I don't feel as deprived as I would if I go on a "diet" and suddenly start eating 1,000+ calories less than I have been.