I make no bones about the fact I am an aromantic asexual person (basically, I don’t want or need sex, and I don’t want a romantic relationship), so I have included some pages and articles below for those who are interested.
The first stop for anyone should be AVEN (the Asexuality Visibility and Education Network) at http://www.aven.org. AVEN hosts the world’s largest online asexual community as well as a large archive of resources on asexuality, and strives to create open, honest discussion about asexuality among sexual and asexual people alike.
This article about Asexuality & The Rise of Sexual Minorities, by James Mazarakis, explains the asexuality spectrum explains the four different types of attraction, who is likely to feel what, and the varieties within each spectrum.
Stormy O’Brink posted an Asexuality 101: Answers to The Most Frequently Asked Questions, that I think is a great introduction for asexuals and allies alike.