Here are a few lesson's showing all the possible forks in Chess.
Fork Lesson 1 and Fork lesson 2
Predator at the Chessboard Lessons (Double Attack)
1. The Knight Fork - 100+ Page lesson with Lots of Examples
2. The Queen Fork - 100+ Page Lesson with " "
3. The Bishop Fork - etc
4. The Rook Fork - etc
5. The Pawn Fork - .etc
Finally Here is the Chess Fork trainer. It took me a few to understand how to use this, you just pick what type of piece you want to fork with, and then click on all the spots on their game board it would fork the pieces that show up.
Chess Fork Trainer
Fork Video Lessons
Knight Forks - 5 Min Video
Chess 101- Forks - 10 Min Video
Chess Lesson Knight Fork - 10 Min Video
Introduction to Basic Tactical Themes - Forks - 6 Min Video
A Post-Match Interview With Sergey Karjakin
7 hours ago