In the unlikely case you don't know what Linux is, look here. Some kernel patches I use on my systems. If you are searching for something specifically, use these search forms. Random patches for all kinds of Linux software can be found in Crazy Achmed's Evil Patch Repository. See this for some little C example programs and utilities. Some repackaged themes can be found here too. I also mirror some packages here which are no longer available anywhere else.
Considering the large infection rate the latest mail-worm 'W32.swen' caused, I came up with this little script which is a dumb mail-worm implementation for *nix. It is supposed to be disguised as a SuSE security advisory with an attached 'security update' script. The script searches the target's home directory for some email-addresses and distributes the advisory mail to them. Then it gathers some info about the target and asks for the root password for the installation of the needed security update. All that information is send to the attacker. I not going to distribute this thingy in the wild and I urge you not to do this either, but I wonder how many people would actually run this thing.
For the casual user or developer it is often not really clear who contributes how regularly to a certain software project. I wrote this script to determine that information about the GNOME project, but it should work with any software which keeps a ChangeLog in GNU format around. The resulting file when run on a current GNOME CVS checkout. You might be surprised by the results.