Sure, he builds up his own LEGO collection bit by bit, but then making sure his friends have some cool additions to theirs as well? It's great knowing he's got me covered with the little things.
I love all sorts of micro sets because it lets me show off some cool ships and vehicles without having to break the bank (and find shelf space) on the larger ones. Plus building in microscale is so fun because of all the details implied by clever uses of pieces.
My current lineup of micro (and midi) Star Wars ships and vehicles:
(I've also got a micro Batman Tumbler I'm debating giving to my brother or keeping for myself.)