There are links between GeoNames, Wikipedia and DBPedia. Look at our
favorite example "Embrun" :
http://sws.geonames.org/3020251/about.rdf
There is a sameAs link to
rdf:resource="http://dbpedia.org/resource/Embrun%2C_Hautes-Alpes"
and a some links to Wikipedia pages in a couple of languages.
We have generated these links automatically, with the lat/lng being one
factor. This automatic matching works for places but not for other
feature types. If you want you can help us add new links. A lot of links
could probably be derived from dbpedia.
If there is interest in helping manually we could add an entry field on
the edit interface and let users add links manually.
Marc