If you're a sysadmin (and given the fact that you're reading this, you're at least interested), you may be familiar with SAGE, which I've mentioned before. Every year, SAGE and USENIX put on a convention called LISA, the Large Installation Systems Administration conference.
Each year, there are plenty of speakers and programs covering topics of interest to all sorts of programmers and administrators. After the conference, the presentations are put online for the USENIX/SAGE members. After a year, they're released to the general public.
2007's presentations have recently been made available, and all the previous years' are still online.
Even though the presentations are a year old, they're still very educational, and an excellent way to pack in something interesting to your schedule.