Before even opening this thread, I was thinking that you’re already a damn good photographer.
But, you want more to do… how about amateur astronomy? Or, old fashioned photography with film and darkroom fun, or eating wickedy hot peppers, or speed posting on the Dope?
I don’t have anything here…
It fascinates me, the diversity of interests people can have. I wonder what it is that makes them pick one thing over another.
My hobby is wondering about people.
Build yourself an airplane. These are my two choices once I get the garage all laid out properly (and the available cash).
http://www.challenger.ca/index.html
http://www.zenithair.com/stolch701/index1.html
Mountain biking. There are loads of bridleways on IOM and you’re not that far from the world class trails available in Wales.
Bowling! I love bowling, and the team thing is fun. Lots of beer drinking, too…
2 passtimes that I enjoy are:
-Magic (or in England, “Conjuring”). It is an awesome hobby and especially fun when you see the expressions on people’s faces when you have done the seemingly impossible.
-Martial Arts. I study Moo Duk Kwan Tang Soo Do and have found it to be a very worthwhile hobby. You get excercise, you learn to defend yourself, and you learn to discipline your mind.
Take these for whatever they are worth. I enjoy them and think you would too.
Isn’t that what he’s doing right now? 
I recommend D&D. Or paintball. Or Magic: the Gathering. Or painting miniatures. Or Hirst Arts.
I read.
I knit.
And I get on these cooking tears every once in a while. I made a batch of ooey gooey chocolate chip cookies that I had to fight my children for, “No, these are ours. Those are for Grandpa!”