This is Marcel Hesselbarth's classic Multiple Teleport Marking Mod modified in order to work in OpenMW (0.41), though it will also work in the original engine.
It replaces the vanilla Mark and Recall spells and adds 11 more slots to mark and recall to any location in the original game (and also in Tamriel Rebuilt 1612 with the corresponding version). The original Mark/Recall slot still works for unknown locations added by other mods.

See readme for details. v1.2 now allows support for the May 1 beta releases of Skyrim Home of the Nords and Province: Cyrodiil.