Preheat oven to 425°. Fit piecrust into a 9-inch tart pan with removable bottom; trim off excess piecrust along edges. Line crust with aluminum foil, and fill with pie weights or dried beans.
Bake at 425° for 8 minutes. Remove weights and foil, and bake 3 to 4 more minutes or until golden brown. Remove from oven, and cool on a wire rack 20 minutes or until completely cool.
Whisk together sugar and next 3 ingredients in a heavy saucepan. Cook over medium-low heat, whisking constantly, 8 to 10 minutes or until thickened. (Mixture should be a chilled-pudding-like thickness and will just begin to bubble and be thick enough to hold soft peaks when whisk is lifted.) Remove from heat; whisk in almond extract, and immediately spoon into cooled tart shell. Cover with plastic wrap touching the surface, and chill 4 hours.
Arrange nectarine slices decoratively over top of tart.
Microwave honey in a microwave-safe bowl at HIGH 15 seconds or until warmed; brush evenly over nectarines.