I've been contacted by the marketing agency for AccessMyLibrary.com, a "library advocacy site featuring the Thomson Gale's online content." I have no idea what this means, but when he said "The Shakespeare Collection" my ears went up. It's National Library Week (April 15-21) and they're highlighting this "free search engine that is all Shakespeare, all the time." You do have to register, but you can just put in random characters for email and phone, it won't check.
I did cruise around briefly, and I wish I had more time to take this sort of stuff in. I browsed through a prompt book from Romeo and Juliet circa 1841. Those are always neat, since you get to see handwritten notes about the actual production. This one included diagrams of how the scenes would be staged.
The only caveat I can find is that I'm not fully sure what parts are free all the time, and which parts are going to stop being free after National Library Week. It does say that the Shakespeare collection is free all the time, so that's good.