Thanks, Joel. I'll try and figure it out. Penflip hasn't been super-awesome for us – I'd love to find another way to get these hosted in some kind of collaborative fashion but haven't had any luck yet. Penflip's a great idea, but the execution wasn't great, and the author seems to have walked away from it.
Sorry, Ret – we're not trying to block access to it, but Penflip seems to be broken and its author is nowhere to be found. I've been spending as much of my free time as possible looking for an alternative solution – if you have any suggestions and would like to help us get the content moved, I'm all ears.
As a note, you can download the source archive, which is just text files in Markdown. Totally read-able, and includes the images. I'm going to look into other options throughout this week, as Penflip's been wholly frustrating.