Anything you can do to get purchase on the bolt. If it is recessed then vice-grips might be tough. A dremel tool would cut a few grooves so you could get a screwdriver in there. Drill it and use an easy out. Use lots of wd-40 and let it sit... You might also try a soldering iron on the bolt and run it through a few heating/cooling cycles. (Try to unscrew when cool -- duh) Be patient, walk away if feeling frustrated...

IMHO