One of the best examples of such sites is The Encyclopaedia of North Africa and the Middle East at www.lexicorient.com/e.o.  It gives a plethora of cultural, historical, political and geographical information in an easy-to-navigate alphabetical index.  The articles are authoritatively written and include an impressive number of links.  Many entries are linked to short audio-file recordings of native speakers.  Throughout, the writing shows an admirable objectivity.

That site, sensibly laid out, informative and text rich, is certainly a cut above the pretentious www.plumbdesign.com/thesaurus, which describes itself as "an exploration of sense relationships within the english language".  We are told that we can "follow a thread of meaning ... creating a spatial map of linguistic associations".  Actually, this is just a fancy thesaurus where words are linked to their near-synonyms by radiating lines.  Choose "autonavigate" and the lines spread like triffids until the computer objects with a mysterious graphic display warning.