Here are some places on the web to get started!
CrimethInc. Worker's Collective a group of autonomous cells operating to publish literature and undertake other projects to break through the emptiness and mundanity of everyday life in capitalist/stateist society. this is the website of the most active of these cells. those involved would likely take issue with my characterizing them as a group, and insist they were a myth, cultural force, or mass hallucination (or, indeed, a combination of the three!)
Infoshop the primary internet source for radical (specifically anarchist) news and discussion of theory and practice.
Anarchist F.A.Q. frequently asked questions about anarchist theory and practice. a good general introduction to anarchist thought, especially with its format allowing users to pinpoint questions they are most interested in finding answers to. a little too leftist for my taste, especially as anarchists increasingly define themselves as "post-left" (outside the dichotomy of left/right wing politics).