Maybe 3 times a week I go to BrandonSanderson.com with nothing else in mind but checking on the progress bars in his site header. I think it's one of the coolest things an author can do (especially considering the genre's writing habits) to post on the progress of each book. Recognizing that their existence is a gift in itself - I think those progress bars should be updated more frequently and emphasized for the sake of marketing Brandon's talents.
For many authors, progress bars would be.... minimally helpful. Not many authors have as much in the works as Mr. Sanderson, and on top of the workload, Brandon has been writing series after series that just sink their hooks into my mind in a way that not many others accomplish. At the end of each book, I am left with a raw hunger for the next, and those progress bars are like the scent of a juicy steak grilling just for me.
What I really mean to be saying (instead of just making myself physically hungry) is that I think those progress bars have huge potential. How many times have I read someone online say, for example "A new Dresden Files book is out?! How did I not know that?!" By going to that site, I know exactly what's coming down the pipe and have a good idea of when to expect it. That keeps me excited throughout the dry period when I stop following other series until I see the cover in a B&N storefront window. Progress bars keep fans hyped! Knowledgeable fans have got to be good for book sales, right?
Brandon deserves that hype. He writes like a ravenous animal, or some kind of machine that just churns out fantasy brilliance. Whether he is a fearsome force of nature or a fantasy Awesome-o, his writing speed is well recognized at every update of those progress bars. He's got a good reputation because of that speed (which is really time spent) and could probably benefit from making that better known.
It might also help this fansite to post a reflection of those progress bars in a similar fashion. Members who frequent 17thShard can tell you that one of the most recurring topics/posts is along the lines of "when is the next ____ coming out?" or "Is Brandon writing ____ or ____ next?" I imagine some Google searches lead new fans here before they ever get to Brandonsanderson.com, so it could actually be doing Brandon a favor to have them represented here as well.
I recognize potential consequences though. The quality of writing should be considered first and foremost, and having to hit an unofficial "progress bar deadline" to meet fan expectations could cause some stress. Speaking from experience though, I know fans on this site at least are very patient and understanding (though hungry, as I noted).
TL;DR - The progress bars on Brandon's site, if updated more frequently and presented in the right places, could be an excellent marketing tool to keep fans excited and up to date while showcasing his particular, genre-defying talents.