This isn't because it's difficult to find things I think he'd like - on the contrary, that part's very easy. Unfortunately, we share sufficient tastes that many of the things I'd like to get for him, he'd also like to get for me. He's also a much more impulsive gift-buyer than I am; so whereas I'll find something nifty and ponder it for a week or so, he'll find something nifty and I'll find it on our doorstep the next morning.
This has the net effect of me feeling slightly guilty for not getting him as many presents as he gets me (but I make up for this by fiendishly managing to guess what his presents to me are, when I do know they're coming); and perpetually being on the lookout for those rare nifty items that he probably doesn't even know exist.
(I love you, Andrei.)