And what uses have you found it good for?  

I use it in my pool filter

but for any other use it's worthless 

I just spread it out in my yard and did not get one mosquito bite and I ALWAYS get ate up if I don't use spray and I didn't use any spray... so I guess its not so worthless.

There is two kinds of Diatomaceous earth.  I used it to put on my bushes around the house, I put it on the ant mounds.  You have to make sure you get the food grade and not the kind that you use in a swimming pool.

I put this on the ant mounds and they were gone the next time I looked...  and good point on the food grade

My mom used to put it on her garden (food grade of course) and I honesly can't remember how much it worked or not. We also would put it in one of our cow's feed for a dewormer!

I sprikle it in my yard and it seems to help with fleas.  I also put it in the dog/cat areas.  I have even sprinkled it on my non washable area rugs in the house and vacummed it up. 

I think it works.  It's cheap enough to try. 

anecdotal evidence is the best evidence 

I wore my new American flag bathing suit the last time I went scuba diving and I didn't get bit by a bull shark. My American Flag bathing suit is a shark repellant 

After i fill a poop tub with manure, i sprinkle the top with a little bit of DE.  It keeps the gnats and flies off the manure.  

I heard that if bugs touch the DE, they will die, but IDK if that is true or not.

Note: I am using the "food grade" DE

I wonder if the OP was asking about using this DE on horses as in a supplement for Uclers or deworming and more. Dont people sometimes use it this way? I sure in the heck would not, but have read it on here at times..

My chickens love to dust themselves in it when I pour a big pile of it out for them. I've read it helps with mites. 

I spread it around the yard to help keep spiders away, seems to help pretty well

I was thinking the same thing.  I used to feed my old gelding a cup a day as a natural dewormer because I was worried chemical dewormers would be too harsh on his belly.  What I was told in regards to it being a dewormer was that it almost scrapes the parasites out of the digestive track as it moves along.  Don't know if that's actually how it works or not lol but I'm sure if you do a quick google search there is bound to be some research on it somewhere...

I use food grade in my formula 

1 coffee can shreded beets

1 can of water

1/2 can of rice bran

1 hand full of DE

I deal with facts from pictures- DE- works

1.Brings out color 2. Reduces fly larva 3.Builds more muscle 

It does not replace wormers but helps with the daily fight of parasites so more vitimians get to the horse 

Im sure you in a bathing suit is repellant enough

I was acutally asking for around the yard to help with flys, mosquitos and other annoying things like that but I had heard some feed through and had good results.  I should have specified for which use....

Its been weeks since I put it on my yard and I still have no mosquito bites when I am in the yard...  :)  The chickens dig it... lol

LOL,  Oh well, now we know it can be used for alot more, ...

I did the same in a stall and was amazed, I put some in my trailer and it's helped a bunch... I mixed it in with the shavings so it wouldn't just blow out

Right?!