I just a made a lemon cheesecake and it is too tangy/sour, apart from sugar, what can i sprinkle over the top to make it taste better?

Thank you all for your responses, I will definitely use some of them in future. Because I hadn't had any responses by the time I was going to be serving it, I came up with my own solution, which was grated dark chocolate and desiccated coconut, with a swirl of honey, and cream drizzled over it. It tasted yummy.

FYI, here's an article on how to prevent or fix common (over or under) seasoning mistakes. Their advice in #6 (how to fix too-sour a taste) is to add salt, sweet or savory elements...
http://www.onegreenplanet.org/vegan-food/fix-common-seasoning-mistakes/

sweetened whipped cream would balance it out.

Sounds like you're all set to make a lemon rum cake. 3-4 T of good rum. Maybe dissolve a bit of sugar if you think the cake's not sweet enough? We always frost lemon rum cake with whipped cream and toasted almond slices...so another opportunity to bring up the sweetness with the whipped cream.

A fruit sauce of some sort. Perhaps strawberries, since they are in season?

Serve with garnish of blue cheese or feta...the salt and savory flavors will balance the sweet.

Powdered sugar

You could put a meringue on top and give it a quick toast....make it like a "lemon meringue pie" deal.

Canned fruit, drained..pineapple, berries, top with fresh whipped cream.