I googled 'avocado-chocolate mousse', started with this recipe, and made a few changes.
3 C avocado
1 C ginger syrup
1 T pure vanilla extract
1 C unsweetened cocoa powder
Cup open avocados and scoop out the insides. Combine with other ingredients and blend until smooth.
I blended in two batches. I would recommend cutting the avocado into small pieces to make it more manageable.
Oh, and did I mention - for all my vegan pals - it's vegan?!?
*Update 3/8/2013: Added to Katherine Martinelli's Avocado Linky Party.*