Readerville is a book lover's website with a journal-keeping feature. Set up a notebook for jotting down your thoughts as you read a book. Enter as often as you like, a maximum of 750 characters for each entry.
You can set up your notebook to view each of your student's journal entries. If you or your students have websites, you can embed the journal entries, as I've done here, in the sidebar. Currently, I'm reading Everything is Illuminated, by Jonathan Safran Foer.
This is a lot less back-breaking than carrying all those notebooks around.