I've seen tons of confusion and guesses about the various growth bonuses for years, but never any conclusive answers or proof, so I tested them myself (with the kind assistance of IGE).
I can confirm that Temple of Artemis does in fact multiply your total food, not just your leftovers:
It also works in other cities:
Fertility Rites, however, only multiplies your surplus food:
As does Swords into Plowshares:
And Landed Elite:
I tried testing the Tradition finisher as well, but it appears to be broken. It's supposed to give a 15% growth boost to all cities, but the only bonus I was getting was from Landed Elite. I even advanced a turn in case it needed to kick in, but no dice. Not sure if it was an IGE-related problem.
WLTKD also multiplies surplus:
And just for completion's sake (at least I think this is complete.. well, aside from Floating Gardens), so does the unhappiness penalty:
Finally, to go back to the Temple of Artemis, the range production bonus only applies to that city:
Overall, ToA is a far better wonder than most give it credit for, but I'd have to agree that it's probably not worth the opportunity cost.