Arson Network
Go and have a look at http://www.arson-network.com/index.php?class=tutorial explore some of the tutorials, but be warned, some of this stuff is a bit on the shady side. Everything from making keygens to installing backdors using netcat. Does contain lots of not shady tutorials, lots on perl, unix, php and python. Definate bookmark.
Linux Device Driver Kit
This is one for all the linux hackers out there, and you know which type I mean. If you can code, and have a piece of hardware that linux doesn't support, why not make yourself a driver for it? http://lkml.org/lkml/2006/5/24/238 has more details on the kit. Come to think of it, I can code, so I might start making Linux drivers soon. You never know.
.htaccess Generator
If you own a dedicated server, or run a homegrown sever, chances are you'll have heard of .htaccess files. The file that tells Apache who to let in, and who to keep out. If you cant understand how they work, either RTFM, or use this handy generator.
