A couple of months ago Amazon quietly announced public note sharing for their Kindle eReader. I was surprised they didn't make a bigger deal about this great leap forward. You can now read a book with a friend, friends or classmates and share each other's marginalia. I don't know if you have ever passed a book around with everyone adding to the margin notes but I can attest from several such ventures that it is well worth the time. The only drawback was waiting for your turn to get the book or being first in line with completely virgin pages. The last in the queue, of course, gets the full benefit of sharing everyone's thoughts, dreams, reflections and critique.
Now we can do it live and be updated as the group reads through the book in real time. Sure we all have to buy a Kindle or download the free app. to our laptop and upload the same book but trust me this is worth the effort. I assume all the eReaders will add this feature soon.
Geographical separation will no longer limit the members of your book club; you can have an eBook Club. Who wants to read Heart of Darkness with me? Or the Foundation Trilogy? Or Catch-22? Or . . .