Below is a list of projects which include functionality that is similar or related to sphinxcontrib-bibtex. If you know of any other, leave a message on the issue tracker.
Andrey Golovizin’s pybtex, a general purpose Python library for working with bibtex files. Drives sphinxcontrib-bibtex.
Matthew Brett’s bibstuff. Includes a Sphinx extension similar to sphinxcontrib-bibtex, as well as an assorted collection of bibtex tools. This is a fork of Dylan W. Schwilk and Alan G. Isaac’s dschwilk/bibstuff.
Weston Nielson’s sphinx-natbib. This extension is similar to sphinxcontrib-bibtex, and aims to support natbib style citations. Sadly, sphinx-natbib appears no longer maintained and the original repository is no longer available. A patched version of sphinx-natbib, with various bug fixes, is maintained in the test suite of sphinxcontrib-bibtex, for the purpose of comparison. Additionally, a few forks of the original repository can be found on github.
Jeff Terrace’s Sphinx Thesis Resource sphinxtr, is a fork of Sphinx which includes a fork of sphinx-natbib.