Here's a fun effect which works when you move your mouse (and it doesn't interfere with the falling snow effect, so you can have both!)
Go here to get the code - look for Mouse Effects in the left sidebar, near the bottom (it's called the Tinkerbell Mouse Effect).
Click the tab at the bottom to copy it to your clipboard. Go to Layouts > Edit HTML and paste the code just after the 'head' tag, right at the very beginning of the blog.
Isn't it fun? It's really beginning to feel like Christmas now!