Personally, I always hide signatures. I've grown too used to reddit's minimalism.If the sig does not fit the rules. However, most (if not all) sigs that I've seen in here fit within the rules.
As for giant images, +1 for the "it highlights content option".
I think the lockpick idea is good, but I hope there's a little skill game like (insert Bethesda game here). It's better for servers that allow PvP and raiding, and could be disabled (by default?) for the rest.