Lambic beers are a fascinating style unique to the Senne valley in Belgium. They are wheat beers fermented with wild yeasts and other organisms (including lactic acid bacteria - LAB). Lambics can be straight sour beers though more commonly include fruit in the secondary. Popular choices of fruit include raspberries (framboise), tart cherries (kriek), cassis (black currants) ans well as apricots, peaches and various grapes, etc.
Besides the spontaneous fermentation, what sets these brews apart is that they are made with a high proportion (30-50%) of unmalted wheat, utilize aged hops (so as to virtually eliminate the hops flavor/aroma but maintain its preservative qualities), have complex flavors like sweaty horse hair, goaty and other barnyardy odors along with the lactic tang, and they're aged extensively in old oak and commonly blended. Sadly, like many complicated art-forms, lambics are a dying breed. However, the popularity of lambics seems to be on the rise, especially in the US and among homebrewers. However, as its essentially impossible to reproduce lambics outside of its native valley near Brussels, domestic and homebrewed versions are best considered "lambic-style" brews and include mixed lambic cultures (brettanomyces, pediococcus, etc) which are available to the homebrewer as well.
I'm a big fan of black currants and Lindemann's Cassis is a good one, and fairly typical I suppose. Lindemann's is probably the most widely available, though I recommend any of the Cantillon selection if you can find it. Also excellent are the "lambics" from New Glarus brewery in Wisconsin. I've also tasted several homebrewed lambic-style beverages including a pineapple, blackberry, peach and blueberry, which ranged from moderately bad to very good. I do love sour things in general and sour beers like lambics, geuze and oud bruins in particular.
And, yes, chicks dig 'em.
