Widely available? Not sure how to define that, but widely available in decent offies:
Sierra Nevada Pale Ale
Anchor Liberty Ale
Goose Island IPA
Fullers ESB
Fullers London Porter
Belfast Black
Westmalle 8
Augustiner Helles
Brooklyn Lager
Ask me next week though and the list will be different <!-- s:) --><img src="{SMILIES_PATH}/icon_smile.gif" alt="

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edit: Were we including draught beer? If so then I'll add Hooker to the list as it's the only good craft beer that's anything close to widely available.