Ary Farias (Atos Jiu Jitsu) shows a tight armlock from the close guard that can be used as either an armbar or a tricep compression lock.
Ary Farias (Atos Jiu Jitsu) shows and non-traditional armlock from the closed guard. It can set up either a tight armlock or a tricep slicer so use it carefully.
Ryan Hall (Fifty50/Marcelo Garcia) shows a triangle setup from upside-down (inverted) guard.
Shawn Williams (Renzo Gracie) demonstrates an effective modification to the traditional mounted armbar
Old school footage of Mike Fowler demonstrating a sequence of four possible submissions from side control when you have one arm trapped: kimura, straight armlock, wristlock and keylock