My property is certified by the National Wildlife Federation. They send you a certificate, which I framed and have hanging on a wall, but, other than the certificate, it doesn't mean anything.
I can't speak for the other organizations - there might be benefits to being certified by them.
Sherry

My garden is a Monarch Waystation. I have a sign that needs to be put up on the fence.

Sandy

Mine is certified by the NWF and NABA. I have 2 outdoor signs hanging on our fence designating the property as such. It seems the NWF and NABA had identical guidelines. You can fill out paper work and send it in, or fill it out on-line.

My garden is certified by Monarch Watch as a Monarch Waystation. They send you a certificate and a metal sign to display. Mine is tacked to a tree stump in the front of my yard where it has been on display for about 5 or 6 years now.

In their application, I had to list the number/types of milkweed I have available as food plants, and nectar plants as well.

I have attached a link to the requirements and the application for a Waystation. I notice now that there is a separate fee for the metal sign, which used to be included with the certification fee.

Susan

Here is a link that might be useful: Monarch Waystation Application

I was going to have mine certified as a wildlife habitat by the NWF, but then I began to think that it was just a way for them to know who to send tons of requests for money to, so I withdrew it. I kept getting mail from them for quite awhile after that.
So now, its just "certified" by me. :)

Actually, Catherine, it's not just money they want. The NWF used to send me requests all the time to will them my land. That might be okay, but I heard somewhere that they would just sell the land if it didn't suit their particular purposes. So, if I will my property to anybody other than my children, it might be the Hattiesburg Audubon Society. Since my youngest daughter likes the "naturalness" of it, wants to keep the forest and the garden, with all its host plants, she'll probably be the one to live here after we're gone.
Speaking of being gone, my husband and I had already prepaid for our funerals, so we decided to go ahead and get our tomb stones. It's a rose colored stone with a magnolia, a bird, and two butterflies on it!
Sherry

Yes I decided to self-certify mine too. The signs are nice, but really as long as you fill out the paperwork and of course send in your $$, there really is no meaning there. That said, many of these are worthy causes, so if you wish to make a donation, then by all means!