I buy groceries online 90% of the time.
I buy gadgets in store after reading reviews and doing price checks online.
Books are 50% in store and online. I will buy a book in store if I've finished a book before I've bought the next one and I need something straight away.
I buy 100% of my CDs online. In store prices just DO NOT compare at all.
Clothes I buy 100% in store. I would never buy something without trying it on. Actually, I lie. I buy bras in the M&S sale just after Christmas, online.