Good website usability is something most organizations strive for when designing their site. However, too often, what passes for a good interface is based on what a few people personally like. For instance, if there are 2-3 people responsible for the site design or redesign, they will use their own preferences and assumptions for what "everyone" will like. Very little research or quantifiable study goes into the decisions, and the resulting site can be very difficult for the intended audience to use.
Below are some articles and resources for researching good site design.