tbibtools provide a simple regexp-based BibTeX parser that can be used to sort bib files, reformat bib files, list keys in a bib file, and show bib entries matching a regular expression. It is available as both a script and a VIM plugin. It makes a few assumptions about how a bib file should look like.
Invenio (formerly CDSware) is a suite of applications that provides the framework and tools for building and managing an autonomous digital library server. It complies with the Open Archives Initiative metadata harvesting protocol (OAI-PMH) and uses MARC 21 as its underlying bibliographic standard. Its flexibility and performance make it a comprehensive solution for the management of document repositories of moderate to large size.
KBibTeX is a BibTeX editor for KDE to edit bibliographies used with LaTeX. Features include comfortable input masks, starting Web queries (e. g. Google or PubMed), and exporting to PDF, PostScript, RTF, and XML/HTML. As KBibTeX is using KDE's KParts technology, it can be embedded into Kile or Konqueror.
refbase is a Web-based bibliographic manager that can import and export references in various formats (including BibTeX, Endnote, ISI, RIS, PubMed, MODS XML, OpenOffice, and Word 2007 XML). It can make formatted lists of citations in HTML, RTF, PDF, or LaTeX, and offers powerful searching and RSS support. Its OpenSearch and SRU/W services and support for unAPI and COinS metadata allow for easy access by clients and search engines.
RefDB is a reference database and bibliography tool for SGML, XML, and LaTeX documents. Command-line tools allow interactive or scriptable access to the data which are stored in a SQL database. RefDB can also be accessed through a Web interface, a SRU interface, or via editor extensions (Emacs/vim). Libraries for Perl and PHP are available for programmers. RefDB provides sophisticated character encoding handling, using Unicode by default.