If you wish to download some of the original essays and the some of the actual chaos magic grimoires you can find it here:
http://www.occult-underground.com/chaos.html
If you scroll down past the description, you will see “Free Ebooks on Chaos Magick”.
It is an interesting magical practice even if it is seen as dangerous...I wouldn’t think you would ever learn anything new without pushing the boundaries....although, better them than me.
Sigil magick is a very personally related to me as I have the name of the angel whom I was named for tattooed on me in the sigil language of the angels.
That web site also has many, many other books on the occult for free download. (use with care)