The slides for the majority of the talks of the 21C3 are now available through the “fahrplan”. Their individual download link is located on the detail page for the single lectures.

If you are too lazy (like me) to click though all single detail pages to obtain the slides, you could try this link, but be forewarned: the URL might not be final and might be subject to potential future changes.

[21C3 Weblog]