I travel to Greece quite a lot, the most useful sites i've found:
http://www.gtp.gr/
free to register
http://www.robby.gr/
Hellenic search engine
http://www.travelling.gr/
http://www.gogreece.com /
You
could also try the Lonely Planet Crete book, sadly not online.
As far as the language is concerned, i bought a copy of the Lingaphone PDQ - Greek for English speakers.