Using giveaways to build your list is becoming an increasingly popular method, and providing you do it right it's easy to generate a large amount of subscribers in very little time.
A giveaway event is basically a website where marketers upload products for other people to download for free. These products can be anything – eBooks, short reports, audio products, video products, etc.
In order to gain access to the products, people first have to sign up to the giveaway event (so the organiser of the giveaway gets to build their list) and then people also have to opt-in again to download any individual product (so the person who puts the product on the site gets to build their own list.)
Contributing a free product to a giveaway event can therefore be very lucrative. People sign-up to giveaway events because they're looking for free products, and if you can provide a product that people want then you should generate plenty of new subscribers.
The most important thing is that you give away a QUALITY product. Many people upload products to giveaway events that are outdated, tired, and are generally rubbish.
You can’t offer crap. Sure you'll get opt-ins, but if the product is rubbish then people will very quickly unsubscribe.
The other thing to consider is the quality of the giveaway event. Some giveaways seem to be put together in a great hurry, look very unprofessional, and have lots of rubbish products. Do you really want to be associated with a giveaway like that? Probably not.
It's a good idea to promote the giveaway you're participating in. By generating referrals to the giveway you will in most cases help your product appear more prominently in the giveaway. On some sites it is a requirement that you generate a certain amount of referrals before you are allowed to contribute a free product.