In a recent topic I posted this:

---

To whoever's post happens above roflfuckyou's, if she is to post in this topic.

---

Should it be whoever's or whomever's?  

-------
I snort like a true woman. - CherryD
It was he.  HE!  That man.  Yes.

Post edited at 8:42 pm on Dec. 1, 2008 by Praise the Lard

-------
Shoot to kill, aim to please
What good's a heart if it ain't on your sleeve?
Falling in love is a losing game
It's fun to play, but it ends the same

I freakin' tried.

-------
Caution when hot.
You've given me strength to find hope.
Packed with speed games and brainteasers everyone can play!
Severe ultra MEGA porn.

will you ever listen to me?

-------
This blood on my hands is something I cannot forget.

That's a keeper.

For the record, in most English dialects, 'whomever' is more or less defunct.  I would say that it's generally appropriate to not use it at all.

-------
We aren't gonna die. We can't die. You know why?Because
we are so very pretty. We are just too pretty for God to let us die.

'person' suspended in ellipsis, 'whose' + 'ever' --> "whoever's"

-------
We aren't gonna die. We can't die. You know why?Because
we are so very pretty. We are just too pretty for God to let us die.