PopCap offers a free Peggle Nights game for the PC or Mac for your friend when you sign up for their Passport membership along with their newsletter subscription. The sign up process is easy, and it only takes a few minutes. You will receive a confirmation email from them after you sign up. Follow the link provided in the email to the page and look for the link Gift-a-game. You can only send the game once. The game retails for about $19.00 and has a high rating.
Here is the link to the signup page.