In Bellingham (WA, USA) we sing the round:

We wish you a very merry birthday
A joyous and celebrated birthday
Our friend _______
We wish you a long long life!

Also, the Harry Chapin words to the Merry Widow Waltz come out like this:

Happy Birthday, Happy Birthday. We love you.
Happy Birthday and may all your dreams come true.
When you blow out the candles one light stays aglow
That's the love light in your eyes where 'ere you go.

Also (not so mean):

Why was he (or she) born so beautiful
Why was she born at all?
She's born for the joy of everyone
She's born for the love of us all
(continue to almost the tune of My Bonnie Lies Over The ocean)
She ought to be publicly cuddled
She ought to be publicly praised
She ought to be fed upon chocolate
And given time off and a raise!

And of course we sing the birthday dirge. In our family, we sang it this past spring for my 92 year old father, who conducted us all, and grinned when the folks in their retirement home looked horrified.