SANS
If you are interested in computer/server/network security then the SANS Institute (SysAdmin, Audit, Network, Security) is a must bookmark in your browser. Some 3+ years ago they started publishing, weekly, a list of newly found vulnerabilities. This weeks list is the largest they have ever published and its breadth is truly stunning. Check it out.
If you host your own domain and you are using PHP in certain ways your server is very much at risk. Fortunately there is already an update available at php.net
