Carpet Moss

So I am looking to add some sort of ground cover, like a moss that can form a natural carpet in part of my aquarium. What would be the best to do this?

I know of XMas moss but that don't grab and hold root too well.

Java moss?

I also have somebody who said he can sell me some HM/pearlweed if I am interested. However I have heard that if unmaintained it can grow very tall.

Is there anything that will only grow to be about a inch tall or less and act as a good carpet? Mostly for Cherry shrimp and their shrimplets.

I wish I could remember the name of the grass I have growing in my shrimpery, it's formed a great carpet, although the leaves are about an inch long because they curve downwards the carpet height is actually only 1cm high. Its a very popular hangout for the shrimplets and pygmy cory fry.

Thanks for all of the links, I will have to look through them and maybe order a couple to find what fits right.