[AndrzejB]

I am wondering about openCyc, UMBEL, PROTON and DBpedia. How can I use this databases?

[ivan.moony]

Some of the databases provide data in CSV format which can be opened by regular programming databases, I'm sure there is a plenty of free libraries on the web for reading CSV data. Otherwise, I guess you'll need to parse files with something like http://pegjs.org/

[spydaz]

There is a software called fluent editor ... To handle owl ontology files