The following is a list of websites to groups that I'm involved with and/or websites with information that I frequently read.
Note:BSD (Berkeley Standard Distribution) is one of the original Unix operating systems developed at Berkeley University. OpenBSD, NetBSD, FreeBSD, etc... are all operating systems based off of BSD Unix. From a users standpoint BSD is very similar to GNU/Linux because GNU/Linux is based off of Minix which was a minimal Unix operating system geared toward eductation purposes. Hence if you're familiar with Unix, Linux, or Open/Net/Free BSD you should be able to figure out how to use any of the others.