*Once you've collected a bunch of content that brings people back to your site, consider writing an ebook.
As an affiliate program promotion web tool, ebooks make great giveaways. In fact, it might even be a good idea to find related sites and offer your ebook to them for their visitors or customers (the more copies out there the better, as many readers will come to your site after reading the book. You could even offer to let them "co-brand" the book and add some information and links to it so you both benefit.
When writing an ebook, be sure to make the information genuinely useful--but don't be bashful about putting a plug for your site throughout the book.