Delta currently has a number of outstanding fares for travel between the U.S. and Europe with tickets costing as little as $317 roundtrip.
- Washington DC to Dublin for $317 roundtrip
- Washington DC to Istanbul for $418 roundtrip
- San Francisco to Dublin for $377 roundtrip
- San Francisco to Moscow for $375 roundtrip
For a full list of routes available as part of this deal, see this The Flight Deal post.