My idea would be to try to create a series of rings that have certain visual effects that already exist in the game.  I stole this idea from an existing mod actually, but which was never officially released as it was buggy.  So I thought this would be a good project to start to learn the official modding tool.
Like a "clean ring" that would remove all grime and blood, like after a long rest.  A sweat ring that would make you look all sweaty, a blood ring to make you bloodsplattered, that kind of thing.  I think that some other effect could be added, like the bloodsplatter ring could add 1 to intimidation checks, or the clean ring +1 to charm checks.  Well, just seems like a fun thing.
But first I need a "modding for dummies" intruction manual.  Thanks for the references.