Iain Abernethy is a British sensei who studies the grappling applications of the Wado Ryu katas. Since Wado's master Otsuka learned some of his katas from Shotokan's Funakoshi, Iain's contributions apply very well to Shotokan. Iain and I have a lot in common.
If you do not own Iain's DVD on the Heian/Pinan katas, you should drop everything and buy it. He provides sound, practical applications for every move of the five Heian katas. I cannot recommend it highly enough. In Shotokan's Secret, Expanded Edition I said you would go up a dan rank by watching this DVD.
Iain has published many DVDs and books on related topics. I have them all. You won't go wrong with any of them, but the Heian DVD is the jewel in the crown. Buy it now.
And he's fun to watch. His cheerful enthusiasm is quite infectious. He makes joint-locking and neck-breaking seem like good, clean fun for the whole family. I smile whenever I think of it.