Just found Daily Lit - on sign up you have a choice of around 160+ public domain books (so a load of classics like Austen, Dostoyovski, Conan Doyle, Verne etc), they will then send you a portion of the book daily (you can specify frequency to include/exclude the weekend, only Mon/Wed/Fri etc) at the time you choose.
If you suddenly get really gripped and can't wait to get to the next part, you can get them to email the next portion immediately so you don't HAVE to wait until the next day. Sounds like a neat way to get through something literary without taking up huge chunks of time. Also makes a change from Viagra spam.
Just signed up for Twenty Thousand Leagues Under The Sea by Jules Verne.