Here's a couple ideas i had for SCP's, I don't know if they've been done before or if they're any good.
1) A nanite cloud, that is connected to a small wireless transmission device. The nanites constantly mutate and modify themselves in an attempt to escape containment. Mutations may include increases in intelligence, function and autonomy (I would have the wireless device originally be a coordinator of sorts for the swarm.) Maybe it could be implied that a rival organization is using them to attempt to sabotage the Foundation in some way. There are very few SCP's that incorporate organizations like the GOC (other than the rash of articles that incorporated AWCY) into them.
2) A block of marble that, when looked at directly, takes on the form of a person or thing that the viewer hates more than anything else, it then uses taunts or other means, all of which would correspond to the real version of the person or object of course, to provoke the viewer into attacking it. Damage done to the SCP is reflected onto its attacker… the worse off the attacker is, the more the SCP does to try to provoke attacks.
just throwing these out there.