That sounds very nteresting, but the first thing I would ask for is actually an auto mark when I looked at the details and sort them by date marked and clear all marks.
It's actually also a very big job that does a ton more than my original idea. Which isn't bad, but if my original idea is interesting at all, I may have come up with a simpler way to implement it. What i was thinking about was perhaps a function just like the widgets that keep track of the last books opened. I beleive that didn't require a database change because you limit it to a small number (20?) of books. If you did the same storage for books looked at, you wouldn't need a database change and no one would ask you to sync it to calibre. Then if you also added an way to look at the list in cc, I would be all set.
I would prefer this within cc, because my next step after looking at the list is to look at details again,not to open the book.