If a genetics laboratory can be compared to the high fashion runways of Milan, then Cre mice are the latest, trendiest clothes around. (Traditional gene knockout mice? That was so last season!) Cre mice, conditional gene knockout mice in which the Cre/loxP recombination system is employed, have become the new standard in genetics research. This is because they allow for the targeted knockout of a gene within specific tissues and at specific time points during development. Because of the advantages of the approach, Cre lines are constantly being developed and expanded. So, thank goodness that the Nagy laboratory at Mount Sinai Hospital has compiled Cre-X-Mice, a database of the myriad Cre lines. The site authors concede that it is not a complete compilation, but the framework is certainly there. Visitors can search the database by anatomical area, cell type, developmental stage, promoter or locus, transgene type, and genetic background. This is definitely a database to bookmark as researchers continue to concoct their transgenic “Cre”-ations.