I decided to create a Birthday Module to learn the Google Homepage API. I think that it's a handy widget to have on your home page, but I admit that entering the birthday data is a little difficult because you have to enter all of it in one box. Even though Google-provided modules, such as the Stock Market module, allow you to support a variable number of items through the module's preferences, that capability is not available to modules created with the Homepage API. (Hence, one box with a lot of data delimited by semicolons.)
Also, I have bundled a small Easter Egg with the Birthday Module -- try to be the first to find it and figure out how I hid it!