I climb a hill on my return trip home that is a 12% grade over .7 miles. The thing is murder! Funny thing - I don't even have to go this way unless I choose to. . . and I do about once a week. I'm striving for CKOM (Commuting King Of the Mountains) in this town
Edit: And I'll also add that I only have a double (39/25) and I also have loaded panniers, so it is a bit of masochism.