Ok, I've got agar-agar. I tried making jelly with cranberry (juice drink, I know, I know) and some dried cranberries, and it tasted ok, but didn't really gel. It was properly cold by the time I served it, but it was a bit loose.
The instructions on the agar-agar were really specific, and I followed them pretty closely. (quantities, and also no stirring before boiling, then stir) The agar agar definately did melt. DH thinks the acid in the juice kept it from gelling?
Any ideas?