Esus has announced the release of Acronyma, a search engine with an index of over 450,000 acronyms and abbreviations. It’s available at http://www.acronyma.com/ .
You may search in several different languages, and you may search by word or by acronym. I searched for the acronym Yahoo and got one result (Yet Another Hierarchical Officious Oracle). I searched for Perl and got four results, then searched for Pine and got three results (including the expected “Pine is Not Elm”.) Results are listed by relevance/importance or alphabetically as you prefer.