The following suggestions/complaints pertain mostly to the websites of small publishers and academic presses, as they are the ones I most frequently visit.
1. Better site search capability.
If I had a dime for every time I typed in exactly worded title and author names only to get a 'no results' message in return ... You know the page exists because you can get there through Google or a sometimes labor intensive site browse search, so why these search boxes are so often useless is beyond me.
2. More frequently updated release day information.
Most product webpages never update the original release date. With actual dates increasingly missing projections by wider and wider margins (or at least it seems that way from my observations from 2005 to today), some effort should be made to periodically reset them. It's frustrating to visit an unpublished title's page in October and see the release still set at February of the same year. Users are also frequently left unable to discern whether a past pub-date book is truly available or not. For every site that incorporates a preorder button or a' forthcoming' tag, there is another that provides no notice either way.
3. Keep product links "alive" longer.
Early on, I was happy to link my reviews and other posts to the dedicated product pages of publisher websites, but quickly switched the practice to just general home page links due to the epidemic of expired URLs. My posts are designed to be more or less permanent and non-fiction history books have a long shelf life, so I have no desire for the CWBA site to be filled with dead links. I think it would be beneficial for all involved to have links to book pages remain the same for as long as possible while the book transitions through its publishing life cycle.
4. More product information.
At this point, the e-commerce sites do a far better job of informing prospective buyers of the content of books than the actual publishers do. Some outliers offer useful things like videos and sample chapters and maps, but the overwhelming majority just go with the traditional cover art and product description (the latter varying widely in the qualitative summarization of actual content). At a minimum, I would like to see a full table of contents for all non-fiction titles. I've yet to see anyone allow consumers to view or download the bibliography, but have often thought that might be a marketing tool of promise for niche titles. Would that be viewed as 'giving away too much'? In my opinion, no.
Time is money, and most small publishers are stretched as it is, but the above seem (outwardly at least, to me) relatively inexpensive ways to improve the consumer experience of surfing publisher websites.