Here are some pics of a cover I made from a Rolodex business card book. I went to several office supply stores, taking my Cybook with me for sizing. There are all kinds of styles available: vinyl, leather, faux leather. The one I picked was nice fabric with a flexible faux leather spine so it folds back nicely, and it fit perfectly! I got mine at OfficeMax for $10; Staples has them, too, or it looks like you can buy one from
Amazon for $8.40, but make sure you get the right size.
Inside the front cover is a clear pocket for a business card, and a faux leather pocket at the bottom. Both covers have fabric panels with openings towards the spine, into which were originally inserted the "cover flaps" of the vinyl business card file; that I just pulled out and discarded (get it... dis-carded? ha!) It came with an elastic pen holder loop that I trimmed off with scissors, along with two other tags that said something like "Made in China". You can see remnants of the pen holder near the upper right, and one of the tags near the center of the spine.
I put two wide strips of self-adhesive Velcro (the hook side) at the top and bottom of the back cover, trimming the rounded corners slightly. I got the Velcro from Jo-Ann fabrics for a few dollars. I put narrower strips of the softer loop side on the back of the Cybook as shown. Why did I use narrower strips on the Cybook? I figured wide strips would stick so tightly it'd be hard to pry the Cybook loose, and I think I guessed right... even the narrow strips are hard to separate, so the Cybook is quite secure!
I can hold the covers and read like a normal book, or I can fold the front cover back and read one-handed. My only complaints (with the Cybook, not the cover) are that the page turning button is WAY too stiff to use comfortably, and it occasionally fails to turn the page, even though the light blinks. This is definitely due to pressing it in a certain way, as I can reproduce it fairly consistently.