It looks like WDWMagic is going to be making its own crowd mid-May!!
Sweetpee's right, it does get much more crowded towards the end of May and Memorial Day.
We usually go the first week of May for our anniversary, but have gone as late as the week before Memorial Day, and what a difference in the crowds and the weather! Light crowds and perfect warm blue skies at the beginning of the month give way to heavier crowds and hot humidity towards the end.
All you guys, look out for my WDWMagic button from May 15-19, and if you see me, say hello! The button is usually attached to the strap of my backpack (it's a pocketbook, really, but has backpack straps--don't be looking for a big hiking-type backpack)