Hi,
I believe the most important database of articles in
the high energy physics field is SPIRES. It would be
nice to have support for that. See the webpage at
http://www.slac.stanford.edu/spires/hep/search/index.shtml
Another of my favourites on the mathematical side is
MathSciNet run by the AMS (in contrast to the previous
one this requires the institute purchasing it)
http://www.ams.org/mathscinet/search
In both cases one can obtain automatically generated
bibtex entries. Since in particular SPIRES is rather
quick in taking up new eprints it might be worthwhile
to think about a feature implementing an automatic
update service for existing jabref entries based on
this database.
Best wishes,
Thomas
A MathSciNet plugin would be very useful.
An INSPIRE fetcher is already present and fetcher for MathSciNet as well as Zentralblatt MATH will be added with https://github.com/JabRef/jabref/pull/1929 (hence should be available in JabRef 3.7)