If you're really willing to push your own limits, try The Wild's sour/wild beers. I became aware of them last year completely by accident, in a trip to UK, and loved their Modus Operandi beer. I also had another very light pale sour wich wasn't remarkable compared to the first one, but fairly ok. (I guess it probably should have had more time in the bottle to develop and reach its full potential).
Sours beers are not for everyone, and the common first reaction to them is negative. But, if one get over that first shocking experience, go on and try it again, people usually fall in love with it.
They are called Wild because they use in their fermentation process, in addition to possible other yeasts, brettanomyces yeast, also known as wild yeast, a different species, found in some kinds of wine and belgians beers (lambics, flanders red), which gives very rustic but complex and delightful aromas to the beer. It doesn't actually makes a beer sour (it actually produces a very small amount of acid only), but "wild" beers usually have other types of what is called bugs (bacteria and other fungi) in it, which does leave a lot of acid to the final beer, making it sour.
They also have regular beers (IPA, Saison, Pale Ale), and they're almost always creative and daring on their recipes. I guess, whether you like it or not, all their beers are worth a try, because those guys seem to take brewing very seriously and you can expect nothing less than quality stuff.
I wish I was still there to taste all their beers.
And a bonus: they're from Evercreech, soutwest. ;) Look it up at their site and see what they've got.