Oceanus Naturals Carrageenan is an all-natural personal lubricant that gets pretty good reviews. I assume it is made primarily from seaweed, or seaweed extract, as that is what carrageenan is.

Oceanus Naturals also makes a warming version of this personal lubricant (also all-natural), but the reviews are less than glowing.  Apparently the warming version is sticky and dries out too fast.