I always wonder why sites like Anna's Archive (and a lot of torrent tracker sites) don't provide .onion addresses. I imagine a significant proportion of their traffic comes from the Tor network, and onion addresses don't have this same weakness that regular DNS addresses have as they're just the key. I can't imagine if they have the servers already up and running, running an .onion address is that much more work considering the resilience it would add and it's existence may even encourage users to access through Tor if they promote it as the primary address.