10 seldom or never used GNU/Linux commands

Guess how many commands are there in GNU/Linux ? My estimate is somewhere between 1000 and 2000. And how did I arrive at this conclusion ? In my bare bones Linux installation alone, there are 1151 commands. I got this figure by running the following command :

$ ls /usr/bin /bin /sbin /usr/sbin |wc -l
1151

And each of these commands or a majority of them can be combined together to perform complex tasks, in which case, these combinations can be considered to be whole commands in their own right. Naturally, it is a humongous task to master all the 1000s of commands available in GNU/Linux. More importantly, it is easier to ignore many commands which make very good replacements of some of the commonly used commands at least for certain functions.

Brock Noland has compiled a collection of 10 commands on his site *cough* "bash cures cancer", which are seldom used by a majority of GNU/Linux users but which in his opinion are a boon for all Linux users if only they knew about them. The commands are pgrep, pstree, bc, split, nl, mkfifo, ldd, col, xmlwf and lsof . He claims that his favorite of the 10 commands is surely mkfifo. But to know why, you should read his article. He has also provided a number of examples of usage of the commands which makes it an informative read.