The first open source version of Ontopia has been released, which you can download from Google Code. This is the same product as the old commercial Ontopia Knowledge Suite, but with an open source license, and with the old license key restrictions removed. The new version has been created by not just by the Bouvet employees who have always worked on the product, but also by open source volunteers. In addition to bug fixes and minor changes, the main new features in this version are: Support for TMAPI 2.0; The new tolog optimizer; The new TologSpy tolog query profiler; The net.ontopia.topicmaps.utils. QNameRegistry and QNameLookup classes have been added, providing  lookup of topics using qnames; Ontopia now uses the Simple Logging Facade for Java (SLF4J), which makes it easier to switch logging engines, if desired. http://www.ontopia.net/