Andrew Smith is an instructor at Revolution BJJ in Richmond VA. He's a first-degree blackbelt in BJJ under Julio “Foca” Fernandez. Smith is a three-time Pan champion (plus a silver and a bronze), a 20x US Grappling champion, and a decorated judo blackbelt. He wrote a nice two-part series on why it's good to train both gi and nogi. I thought the second half, on how nogi helps your gi game, was a good reminder for me and maybe a bit of a kick in the pants to get me out of my kimono a little more often.
Check the article out here.
Two choke attacks, taught by Fernandez:
Also, if you haven't read Sam Harris's two articles on self defense and his start in BJJ, drop whatever you're doing and read them right now.
Self defense is here.
Drowning in BJJ is here.