Tower Records has launched a new online bookstore that offers over 500,000 titles, including many graphic novels, manga, and roleplaying games.  Base discount appears to be 35-40% off retail.  The company is also planning to expand its magazine and book offerings in its brick and mortar stores. 

The move represents additional online competition for brick and mortar comic and game retailers, and some additional brick and mortar space devoted to the categories as well, but it's hard to read it as significantly changing the competitive landscape.  It's more likely a sign that even though books (other than graphic novels and a couple of other categories) are a low growth business, it's a lot better than recorded music.  Tower went through chapter 11 a couple of years ago; it's now owned largely by its bondholders, and is for sale.