I use KBibTeX to manage my references database, but I used to use Jabref. Jabref has a handy feature that can automatically abbreviate journal names to their standard (ISO) abbreviation format. The built-in list of abbreviations is missing a lot of common biology journals, but I have updated it with many biology journals. You can get the most recent version of my abbreviations list from my Dropbox.
I have nearly every paper I’ve ever read stored in a BibTeX database, so I wrote a BASH script to build a list of citations using BibTeX that could be easily copied into LibreOffice Writer. I would prefer to write all my papers in LaTeX, but there are some disadvantages–poor adoption and inefficient track-changes methods–so I have to use LibreOffice Writer instead. None of the available bibliography managers that integrate with LibreOffice seem particularly reliable to me, and I plan to convert my manuscripts back to LaTeX anyway when I put my thesis together.