You can host your birthday card in a static web page (i.e. one that ends in .html); and put this page on a free hosting site. Simply send people the link to the .html page.
Now, there is a gotcha here - the webserver needs to recognise the mime types of the Silverlight control so that it can serve it up. Fortunately, there is a workaround - you can find details
here[
^].
Submit an article or tip
Post your Blog