Apart from museums and galleries it is hard to keep a regular update of events. Unfortunately, the sites that have taken on this task such as the web site of the Municipality of Chania don't seem to bother with updates any more so you will have to find out once you are in Crete by asking around.
The standard way to list things happening in Crete is still to post signs on walls (generally at very short notice) in the cities. Also if you read Greek you can see the Xaniotika Nea newspaper (for Chania).
Museums are the main repositories of culture in Crete and where most visitors head for when wanting a little bit of culture, if only because it is easier to find them than other cultural events and exhibitions.
Galleries there are a few galleries in Chania listed below