My secret weapon is SPLENDA and a sweet/hot mustard
I use real mayo (Helmans), chopped up bread and butter pickles(or sweet relish is fine too), squirt of the sweet/hot mustard (one I use is made by Koops) and a few packages of splenda. I have always been on deviled egg duty at every holiday because noone knows how I make it.
Usually for 12 eggs (24 deviled) I would use about 2 spoonfuls of mayo , 3 or 4 splenda, 2 or 3 squirts of the mustard and 1 or 2 spoonfulls of the relish
Another key is to mash up the yellow before adding any ingredients, After mashing, add the slenda, then the relish...mash again. once I put in the mustard and mayo, I usually get out a mixer and beat it till whipped and creamy... Another key I have is to add the mayo last, that way its not too mayo'ee. We like ours sweet with a kick, but not to mayo tasting. Eye yi yi Wish I could have one right now :):)