The following exercises are for people who are already strong at doing chin ups and pull ups. These are not beginning exercises.
Alternating chin up
This is perfect for those who feels that one side is weaker than the other. By having your head touch one hand at a time, brings the weakness out and therefore you can strengthen the weaker side. Enjoy.
Alternating slide chin up
This is a very hard chin up exercises. This is perfect for those who wants to challenge themselves and increase their difficulty level. Start with bringing you head to touch one hand and then slide across to touch the other hand and back down. Repeat starting the opposite hand. Enjoy.