No Beer,
6ft 7 here and I'm a big fan (you see what I did there) of 'Big Agnes' bags. Clever design and BIG (length and width) as the name suggests, although end up packing smaller than a conventional.
They do a range of synthetic and down bags, I'll not bother trying to recommend one or another as there's loads to choose from.
http://www.bigagnes.com/Products/SleepingBags
An American company, but they are now imported into UK.
Good luck and it's always good to hear from other tall chaps how they get on with kit, so keep us posted.
G
Oh and someone mentioned Snug pack – Many years ago, I contacted them and they made an extra long bag up for me (basically stitched an extra panel in bottom). Only downside was that it tapered right off to minimal width at feet end. No good If you've got size 13s on the end of your legs!