Indeed, years ago we here at TMC used to quote another Options info site, but that stopped immediately after they went to a required-login model (I get enough spam already, thnx)
The only other free-to-the-public, available-to-guests Options info is from the (nearly unusable) NASDAQ website. I won't even bother linking to it, it's interface is a mess.
So, Max-Pain updates Open Interest daily at 7 a.m. ET and Options volume at indeterminate intervals throughout the day. It's the best I've seen that's freely available to the public.
Cheers!