They say one of the best ways to learn is to teach.
In that vein, my daughter asked me earlier about spelling Monday.
To try to help her remember, I told her that it was a corruption of Moon-day (true). Well, then we needed to talk about the other days. Sunday, of course, refers to the sun.
Tuesday goes in a different vein; I remembered it as being Tyr's day. That's roughly correct, although Tyr is a corruption of Tiwe, one of the Norse gods of war.
Wednesday is a corruption of Odin's day (via Wotan), Odin being the chief Norse god (sometimes called 'Old One-Eye').
Thursday comes from Thor, the Norse god of thunder and war (by contrast, the German is Donnerstag, Donner being thunder).
Friday comes from Freya, Odin's wife, and an important goddess in her own right (though I can't remember specifics beyond her involvement with the Brisingamen).
And Saturday I hadn't previously considered, though it seemed likely to involve Saturn, the Roman incarnation of Zeus (which has interesting echoes to both Thor and Odin, thinking about it). That one I needed to look up, but it does turn out to be correct.
Kind of funny: two days after celestial bodies, four after Norse deities, and one after a Roman deity. Strange mix.