Yeah totally possible. PayPal supplies an HTML form as part of the code they give you. All you need to do is add a hidden element with a name of notify_url and

Yeah totally possible. PayPal supplies an HTML form as part of the code they give you. All you need to do is add a hidden element with a name of notify_url and set the value to a PHP script on your site. PayPal will do an http post to that script and one of the fields they post is payer_email, so you could set up a PHP script to email the ebook to that email address. Now, this is all horribly insecure - if someone discovered the name of their script you can see how easy it'd be to get it to email the ebook to whoever - but for no-cost boot strap solution, it'd do the job initially. I'd happily lend you a hand getting started with this stuff, my email address is in my profile.