These have been for sale for a while, but since I think they're awesome (and I suspect that the sooner they're sold out, a new volume will be released) I'll tell you about them anyway.
The sketchbooks contain sketches and notes from George Jeanty (the main penciller for Season 8). Vol 1 (sold out) contains "extras" for issue 1-5 and the one in the link above, vol 2, has extras for issue 5-10. It shouldn't be impossible to find vol 1 on ebay or in some story, but they might be pricey.
On every book Jeanty draws a original sketch of a character of your choice and signs it(so it won't be blank like the example above or on George's site) Since I got him to draw Tara, a character not in Season 8, I think you could pick pretty much any character you want.
Other than the back and front cover, the book is in black and white. The quality isn't the best, as a matter of fact I've use tape on a few lose pages in volume one. But other than that, I've very happy with the book. And on the back of vol 2 is the most darling Drusilla drawing ever.
I've heard that there's only a 1000 copies of each book, but since I heard it from a fellow fan who's been in contact with Georges Jeanty, I can't say for sure.
PS. In case you want several books, ask if you can get a discount.
Click HERE to see examples of headsketches or HERE (the sites have some of the same sketches)