There are thousands and thousand of pages on the Web on Kundalini, Kundalini yoga, and so on. Some of this material, obviously, is better than other. I've only included a few high google rating pages here, and have ignored Kundalini Yoga websites, because I'm not qualified to tell which of those practices and yoga schools are legit and which are in the category of "a little knowledge is a dangerous thing". Anyway, the above is not intended to be definitive. If you have suggestions for Kundalini links let me know :-)

Wikipedia - short coverage, truies to be academic and factual

Kundalini - short essay

Kundalini - Crystalinks - an essay and introduction to Kundalini; includes theory, meditation, and a large collection of images, some relevant, others less so

Kundalini Symptoms Of Awakening - short essays and pages on kundalini, symptoms of awakening, ch'i/prana, shaktipat, and so on. Some may refer to actually kundalini, otehr refernces and experiences are more generic

Historical Sources & of Knowledge Kundalini - Kundalini in compartive religion, quotes from various historical sources, and also some more contemporary accounts and experiences. A lot of it is pretty dubious, the religious references can mean anythingm, and the experiences likewise are generic experiences of inner, cosmic, or perhaps divine consciousness.