Need Plugin or Widget For Giving Something Away

Hi,

I’ve been searching everywhere for a plugin that will allow me to give away an e-book (pdf) on my WordPress site. One that will automate thr process. I want people to subscribe to my site and in return I’ll give them an e-book. I’m sure most of you know what I’m talking about. Is there a plugin or widget I can use? I have searched all over and have been running in circles, so I thought I’d just ask the pros.

TIA,
Rich