I have seen some of the SQ girls bringing out a birthday cake and singing birthday song to birthday people. They usually do it between meal services. On top of that, once that special amenity has been given, usually the crew sometimes offer to bring food or drinks not normally offered to Y passengers such as hot chocolate from Raffles class and so on. Just remember to give them at least 24 hours notice and they will do what they deem fit. Just don't expect 500,000 Krisflyer miles or automatic op-upgrade and pretend everything is as per usual.

And well, a post on flyertalk would be nice.