low- or non-fat desserts
easiest: frozen fruit. sections of fresh fruit stuffed into individual serving sized tupperware and frozen. grapefruit is good, as are mixed fruits, even apple. nuking about 20 seconds will soften it just enough to get your spoon into it.
fairly straight foward: mock cheesecake (refrigerator type) made from yogurt, no cream cheese. soften some gelatin in water. warm up some yogurt in a pan, sweeten and flavor to taste (sugar, honey, vanilla, lemon, fruit puree...). add the gelatin and stir till it's dissolved. it doesn't need to come to a boil. pour into tupperware or custard cups and let set in fridge.
of course egg whites go a long way too. baked meringues and macaroons for example. you could even do fruit mousses (e.g. raspberry or strawberry) using more egg whites and 86ing the whipped cream.