phylogenetic information. To quote from the web site:
Popular phylogenetic databases such as TreeBASE, PhyloFinder, TreeFAM offer complex text-based web forms for structure queries. Still there seems a great need for intelligent visual query formation based on a phylogenetic query language for content exploration. PhyQL offers a visual query design interface where the user can create simple to complex queries based visual query operators. The query language is translated to a list of datalog queries, then executed in XSB, an extension of Prolog. Separating the application layer from the data layer by a logic layer reduces query tools development time. Moreover, PhyQL offers interactive tree visualization which is very convenient for viewing very large trees.
There is also a YouTube screencast:
I haven't had a chance to play with it yet. PhyQL was originally described by Jamil et al. "Querying phylogenies visually", BIBE 2001 (doi:10.1109/BIBE.2001.974405).