A fun article from TMRZoo listing 10 beers you MUST drink this summer. I agree: Saison Dupont, Erdinger, Prima Pils. I disagree: Landshark Lager, Sam Adams Summer Ale. It pains me to remove a recommendation for the Sam Adams Summer - it, and the Pete's Wicked Summer, was one of the first seasonal craft beers I can remember really enjoying. But it's just too darn sweet for my taste these days - it doesn't warm up well at all. And while Summer beers are almost always great cold-drinkers, they warm up quickly so they can't taste BAD when they do get a little warm.
My own Summer Top 10 (in no particular order):
Furthermore Fatty Boombalatty, Lakefront Organic ESB, Saison Dupont, Stone IPA, Erdinger (hefe or dunkel), New Glarus Imperial Saison, Surly Furious, Coors Banquet, Great Lakes Burning River, Bells Oberon