The DSDT (Differentiated System Description Table) is a part of the ACPI (Advanced Configuration and Power Interface) specification, which supplies configuration information about a base system. ACPI capable computers come with a preinstalled DSDT from the manufacturer stored in BIOS. This is a piece of code in a special language, AML, which is evaluated by the OS with an in-kernel interpreter.
I just discovered mandelbulber by Krzysztof Marczak (buddhi1980), a frequent visitor of Fractalforum. It is an open source program to ray-trace 3D fractals, and in my opinion this is simply awesome. It can be used to render images or even fly-through movies. The program can be found as project mandelbulber on Sourceforge.
I've been using Duplicity for a while now to backup my Linux (virtual) servers. Duplicity is a bandwidth-efficient tool to do encrypted incremental remote backups via SSH, rsync, webdav and many others, for example Amazon S3.
Lately, I wanted debug a problem with NetworkManager. As this service communicates via DBUS I wanted to intercept all traffic on the bus to see what happens there.
Recently I ordered a USBee logic analyzer. The Windows tooling is pretty nice, it comes with built-in serial decoding, which will come in handy (Unfortunately, it doesn't seem to be supported on Linux at all al the moment. Some people are working on it, see sigrok and x-project).