I went to boil some eggs to make egg salad and three of them floated to the top, what does that mean?

Martha agrees with everyone. Floaters have gone bad: http://www.marthastewart.com/article/eggs-101

Glad I asked, Thanks all!

I am with pierino - it just isn't worth the risk.

Myself, I would not even consider eating or serving an egg that was a full on "floater". Tips fine, but the whole egg, never.

Heylucy is probably correct but I would not use the eggs that floated to the top. It's not worth taking the time to boil them to find out they were bad. I would boil fresher eggs. If you really want to be thrifty, crack the eggs you are uncertain about into a bowl one at a time to make a determination on their freshness. If they are still usable bake with them.

It probably means that they are not as fresh as the others. Did the whole egg float, or just the end? As eggs get older, the air pocket between the shell (which is porous) and inner membrane expands. This isn't necessarily bad, I have chickens, and never use the fresh eggs for hard boiling, because the smaller air space means that they are much harder to peel, so I always use eggs that are a couple weeks old. I would peel them and see how they look, if it was just the ends that were floating, you should be fine, if it was the whole egg, they might be too old.