The best professions for passive income on alts?

Hi, I came here for an advice. My Wotlk main is going to be Ele shammy mainly for PvP purposes. My professions are going to be JWC and ENG.
I also have lvl 70 prot pala, rogue and a mage. Is there any profession that would be nice to have on my alts for almost passive income?

To clarify a bit, I'm not looking for a guide saying - level your prot pala to 80, boost etc. I'd like to spend most of the time playing the ele shammy, but I was thinking that maybe I could use some alts to make transmutes etc.

I remember I had a LW 35shaman back in Classic Vanilla, I logged in every 3 days to make the cured rugged hide and had a decent profit from it. So I was thinking about something similar that doesn't require too much time in order to make some income.

Thanks