I've got another SCP and associated data log on the burner. One sentence description: it's a Foundation Observation Post (a la Raven Mackenzie's story "To Sleep, Perchance to Dream") which appeared under mysterious circumstances and, instead of receiving Foundation monitoring data as expected, receives such data from alternate Foundations in alternate realities/dimensions/timelines/universes. A black box device lets Foundation scientists "dial in" to other universes and receive data from those universes. The log records data from different universes.
That's the short version (I'm of the opinion the long version is better than my short summary). These are sitting in my sandbox under the titles "SCP-XXX" and "Data Log XXX".
I'm figuring this will work as an interesting engine for looking at roads-not-taken by the there-is-no-canon "prime" universe. I've started the log of with a couple of short bits, including two short audio logs from a civilian boombox radio set located in SCP-XXX. More of these might happen as I have time, inspiration, and available voice actors.
(Also, I have spoken to Raven Mackenzie about using Dr. Mackenzie and cleared the reference to Dr. Clef's Proposal with Clef.)