Giving away freebies is called "ethical bribes" - and is a standard action. But you ALWAYS "give it away" in exchange for at least their email address, where you follow up with subsequent messages.
I gave away hundreds of copies of free books through my Lulu site and found I started really making money when I quit. My current plan is to take those same freebies and turn them into autoresponder email series to convert those viewers into buyers.
But she gives a lot of great ideas to create freebies on this page. Just get their email address, first.
Publishing Basics… for the self publisher » Offer Freebies to Increase Your Website Traffic: "Promoting Your Freebie
Once you have decided on the freebie(s) you will offer on your website, the next step is letting the world (or just your target audience) know that the free product is available. There are a number of ways to go about doing this. First, place the free product information prominently on your home webpage. Then, include the information in newsletters you send to your customer base. Write and distribute a press release about the free product. Finally, submit the free product to “freebie” directories on-line such as www.freebies.com.
These ideas are just a beginning of potential freebies. Offering free downloadable audios of an author’s talk at a speaking engagement can help increase your fan base. Having a gallery where fans receive a free book related product such as a screen saver based on a book also entices fans to “come back for more.” Hopefully, the ideas listed here will spur your imagination to bigger and better thoughts on what you can offer your current and potential customers to increase your website traffic."
update 071018: Now, giving away podcasts of your speaking moves into a different format. This is like giving away viral ebooks. Just make sure your podcast has an ad (preferably beginning, middle, AND end) of where the listener can get more data from you. Again, I'd say to get their email address first, or give these away because they bought your book, etc.