Firstly, jammies. My little man is a skinny-minnie-miller, so he always outgrows things in length before he outgrows it around. Too easy. So what I've done is taken all his 1T size jammies that are too short and lopped them off into shorts and t-shirts. Save a little money on new jammies and it literally takes about 5 minutes to do, max.
(my 'before' and 'after' pictures are of different sets of pjs that both got the summer-treatment. Can't find the guitar ones anymore. Silly laundry.)
Now for the good stuff. It may not seem summery, but check out this super awesome poncho knitted by Grammie!
He loves it, and while it's still too big, he NEEDS to wear it (he gets testy about shoes and sweaters for some reason; everything else he could care less about). It's perfect for our Canadian summers, especially early in the morning, out playing in the yard before the sun has really warmed things up.