Avatar is probably the most infamous example of multiple aspect ratios. The 2D theatrical was around 2:35.

Voyage of the Dawn Treader also caused some HT enthusiast teeth gnashing over the home video transfer.

Does the recomposed for 4:3 home video version of Pixar's A Bug's Life count? (They literally re-rendered the entire movie.) I don't think they did it for any other films, and pretty sure they didn't port that over to Blu Ray, so it may be as obscure as the full frame version of Lady and the Tramp is now.