Basic Linux and Linux Utilities using Youtube and Webpage
Linux tutorial 
Ubuntu tutorial 
My favorite distribution is Ubuntu.
Here is a good starter video.
Emacs tutorial 
Xmgrace tutorial 
A great tutorial by Vyshnavi Vennelakanti:
Another tutorial video on Xmgrace is
But there is also good text-based user guide for looking up commands:
 Latex tutorial 
Here is a great text that gets you stated with Latex:
  
Here is a great Latex Tutorial by Aaron Wong. It was originally made for maths
students (so there are some part explained that you may not need),
but it is actually great for every one who needs to write equations.
Just to be clear, you do not need to know this all to create nice latex documents.
The first five videos give you a great start!!!
 Just Enough LaTeX to Survive
  
Individual Videos:
  
Even if I love Latex, I do not recommend to prepare talks in it. I used to do it for years for talks,
but I realized that PowerPoint is much nicer to use, offers more options, and
creates less problems when you give talks elsewhere.
Here is transcript of the videos
  
 MarvinSketch to draw chemical structures 
  
 XFig tutorial 
  
 InkScape tutorial