DAN (
www.daneurope.org) provide medical insurance for members, but as far as I could make out from the literature, its remit extends to diving related injuries only, so you'll still need regular travel insurance.
You can take out DAN's "travel assist" (or whatever it is), but from what the nice lady at DAN told me, this is also medical insurance (extended to include non-diving circumstances), not travel insurance. So even if you did take out this option you'll still need insurance to cover your possessions, flights etc.
Join DAN anyway - it's a good cause.