BibTeX-Ruby is the Rubyist's swiss-army-knife for all things BibTeX
It includes a parser for all common BibTeX objects (@string, @preamble, @comment and regular entries) and a sophisticated name parser that tokenizes correctly formatted names; BibTeX-Ruby recognizes BibTeX string replacements, joins values containing multiple strings or variables, supports cross-references, and decodes common LaTeX formatting instructions to unicode; if you are in a hurry, it also allows for easy export/conversion to formats such as YAML, JSON, CSL, and XML (BibTeXML).