There are many options for finishing the charlotte. Any flavor of mousse or custard would work. Here are some ideas, beyond the lemon curd and mousse, to get you started.
• Layer of melted chocolate on base, topped with chocolate mousse and fresh raspberries.
• Chocolate mousse with layers of grated chocolate, mini chocolate chips or toasted finely chopped nuts.
• Strawberry mousse (strawberry purée mixed in with whipped cream) with diced berries atop
• Vanilla custard with toasted shredded coconut in layers (for a coconut cream pie effect).
• Vanilla custard with layers of bananas and graham cracker crumbs or vanilla wafer crumbs (for a banana cream pie effect). Perhaps a drizzle of melted chocolate.
• Two flavors of mousse or custard for a layered effect.
• Butterscotch custard with whipped cream.
• Ice cream of any flavor. (You would need to store charlotes in freezer to keep chilled.) Top with berries or grated chocolate before serving.