How do you keep track of what e-books you've already read?
If you buy a p-book, it's easy to remember the books you've already read - the book in your bookshelf will always remind you. But how do you deal with e-books?
The more e-books I read, the harder I find it to remember and track the books I've read in the past. This is particularly annoying when I try to find the sequence to a book but cannot remember its title nor its author.