Lately I have been using Agar for a multitude of things. I have learned that it is extremely helpful in keeping mountings from drying out. Just mix lightly in potting mix.
It is also great for starting seeds. I have used it mixed with bird crap and the seed stuck in the middle of this little glob. Instant germination. This makes sense since many plants rely on birds to eat the fruit and digest it and then "release" it on another branch or the ground. (I buy bird crap as an organic fertilizer, already dehydrated)
So far in the experiment stage, I have mixed it very, very diluted with wetter water. This is sprayed onto leaves and so far it seems to keep leaves hydrated in very low humidity. This has only been 2 weeks, though.