Cider!
There are lots of places doing really good Asturian cider -- make sure you order "sider seco" or "sider natural", if you're offered something that comes in a champagne bottle, that's not what you're after. Don't miss the cider-basted chicken (with cider) at Casa Mingo: recommended to me by dereko1969 and one of the best eaty-drinky experiences I had in Madrid.
There are two brewpubs quite close to each other: Magister and Naturbier. Neither are really up to much. Magister gives you free tapas with your drink. Also nearby there's a fantastic sherry bar called La Venencia, which is well worth whiling away an evening in.
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