I think my favorite Summer scent is AG Ninfeo Mio, I can make a 1 ml sample of my small decant. Blenheim Bouquet will be nice for Summer as well. I asked Penhaligon to send me a sample of it for my Summer, if they send me a double, I'll be glad to share that one as well.
Let me think what else I have enjoyed last Summer... doh, many hours later it came to me! My Summer 2010 #1 was L'Occitane Lemon and Honey Shimmering, it is being discontinued, but you can still buy it off the website, I think. But I can supply some of that, too.