GATE (General Architecture for Text Engineering) announes some very interesting new tools to be released this summer - http://gate.ac.uk/family/coming-soon/.

Of particular note is the 'GATE Mimir multiparadigm indexing', a search engine that indexes GATEs document annotations (e.g. entities, facts, parts of speach etc.) and enables structurerd seach on these annotations such as:

• {Determiner}{Adjective}{Noun}
• {Person}, CEO of {Organization},based in {Location}

Mimir can also store and utilize ontologies allowing it to augment queries via class types such as broadening a search or translating units of measurement etc. Seems like the query transformation via ontology possibilities could prove quite useful, especially within a restricted domain.

Mimir's java API might also make it a convenient mechanism for on the fly knowledge extraction (e.g. query in indexed collection of content for specific sets of entities or facts).