Hey, I plan on going to Free RPG Day FOR Father's Day! ...
The first year Green Ronin did (because they didn't have it ready in time).
After that a number of companies put them up later (I am pretty sure they are obligated not to put it up the same day) including WotC.
In fact, Goodman Games already has a web expansion for their Amethyst giveaway here (it's on their website, too, but it seems to inaccessable right now).