Amaya is a complete Web browsing and authoring environment, and comes equipped with a WYSIWYG style interface. It lets users both browse and author valid Web pages, with standards including (X)HTML, native MathML, and SVG documents. It also includes a collaborative annotation application (RDF).
Surnia can check an OWL ontology/knowledge base for inconsistency and entailments. It is implemented as a wrapper around first-order theorem prover (OTTER, for now at least). Unlike Hoolet (which turns the OWL into FOL), Surnia just turns the OWL into triples and mixes in axioms.
LPMtool aims to be a complete package management and software distribution solution. It includes basic command line and PyGTK-based utilities for installing and removing packages, as well as tools to publish Web-based package repositories that use a GPG-based web-of-trust security model.