Before JabRef I was using Zotero. There are some features I miss or can not find in JabRef.
I want to add single entries to existing bib-files. Currently I do this with copy and paste the "biblatex-source" tab to the extern bib-file opened in a text-editor.
Sometimes I want to create a complete literatur list entry and get the text to the clipboard. It means it the entry should be outputed (to the clipbard) formated like I would use it in a latex \bibliography. (Sorry for my english!) I use this from time to time to put bibliographic informations into mails (for persons who are not able to handle simple DOIs or bib-files).