The argument most people seem to have against population control is, if it feels good, do it.
I guess i'm not as hedonistic as others--conscience bothers me. You don't break the law flagrantly because you are afraid of the consequences against you. You don't go to vegas and spend your family fortune every weekend because you are afraid of the consequences to the ones you love as well as yourself. Similarly, some people don't want to cause grief to future generations of living things by reproducing what they percieve as the top of the food chain that also happens have the potential to destroy all life on earth, because they are afraid of the consequences to the idea of life, which they love. It's all a matter of where you draw the line. Hal has a point though--I think there must be a big element of self-loathing associated with wanting humans to go extinct. But that's kind of an ad hominem attack.
I'm not really for the extinction of the entire human race, but a little population control could do wonders for unemployment, standard of living, quality of the environment. Everone must see that fewer people=fewer environmental issues (unless you think the environment's not an issue at all, which is a different topic altogether). The population when I was born (about 30 years ago) was less than 4 billion--now it is over 6. By the time I'm 70, I can expect the population to be 10 billion people to be on the planet, most of them cramped up in high-rise apartment buildings and stuck in traffic all day. If you like that kind of lifestyle and you think your kids would like it too, by all means keep producing babies. I'd much rather have the population go down a bit and enjoy life more.
A more interesting (and humorous) site regarding population control is the Church of Euthanasia, whose dogma is based on 4 pillars associated with population control: suicide, canibalism, sodomy, and abortion. One of their mottos is "Save the Planet - Kill Youself"
www.churchofeuthanasia.org