There are a lot of tools out there to help you manage your LaTeX bibliography collection. I just want to mention three of them: BibDesk, Zotero, and JabRef. I am a heavy user for the first one. I run into BibDesk the first time I installed LaTeX on a Mac. BibDesk was the tool that stopped me from writing my .bib files by hand—as I did for a long time. Besides allowing to manage your .bib files easily, it provides a nice service integration with TeX. BibDesk also come with a great intuitive graphic interface, the ability to hook you to libraries on the net, and it allows you to export entries to EndNote, Word, RTF, Atom, RSS, etc. Zotero is another great tool for managing your bibliography if you do not always have a Mac at hand. Zotero is a plugin for Firefox. It provides the same functionalities of BibDesk but with a twist. When browsing over the net, if you run into a site which is COinS aware (libraries, newspapers, blogs, etc.), with a simple click you can store that bibliography entry straight to the Zotero bibliography data base. The bibliographic entries are also exportable to BibTeX, RDF, and RIS—to mention a few. The last one is JabRef. Written in Java, you can easily use it on any platform that supports Java. They also provide a WebStart version of JabRef. As BibDesk and Zotero, you can import/export bibliography entries in a wide variety of formats, add annotations, etc. Also, the ability to use JabRef across different platforms may be a plus if your are moving between Windows, Linux, Mac, Solaris, etc.
...