I assume the purpose of the site is to get people away from the computer and into the museum? Which means everything about the site needs to fulfill that objective in some way, whether that's clear access information or a big picture of awed people standing in front of an exhibit.
One thing that is frequently missing from museum websites is a guide to how long you might need to spend there. I have turned up to a museum expecting to spend the best part of an afternoon there, only to be round and out in half an hour. Similarly I've spent 4 hours in a museum I'd only allowed an hour for. Time guides can really help people plan their day, especially tourists who've come from out of town.