For the orange-maple-vanilla syrup: In a small saucepan, combine 1 cup water with the orange juice, maple syrup and vanilla seeds. Bring to a boil, then remove from the heat and let cool. (The syrup will keep in the fridge for a few weeks.)
For the festive fruit salad: combine the clementines, kiwis, mangoes, grapes, grapefruit and pomegranate seeds in a big bowl. Add orange-maple-vanilla syrup to taste, and toss well.