Those ideas sound great, TH. Knock yourself out.

The only thing I can say that I did was to think about what sort of 'person' the Wind would be, what sorts of things she'd be interested in as I built her portfolio and persona. As far as there already being a Water goddess, I don't believe so. There's Delanor, but he's an I
ntermediate Deity... too good for the likes of us Lessers.
One sister goddess for each element springs to mind, but that makes them seem really important. I was thinking that would be like all the myriad nymphs of Greek mythology. There were TONS of them and they did really cool stuff, but weren't the big movers and shakers.
Brainstorm:
Rain and Crops
Snow/Sleet/Hail and Winter (but there could be a Rain goddess AND a Snow goddess)
Mist/Fog and Secrets
Rivers and Agriculture/Travel
Trees and Strength/Wisdom
Night and Lovers
Night and Animals
Wilderness and Hunters
Stone and Community (great idea TH)
Stone and Cities
Fire and Inspiration
Fire and War
Fire and Destruction
I'm gonna ruminate for a while.