Ejunkie has free affiliate programs for all those merchants that have opted for them, so it is just a case of signing up for an account at Ejunkie and then searching on the site for relevant affiliate programs to promote, ebooks are the best products to promote, although there are other options such as digital downloads like audio and video that you could promote as an affiliate promotion.
One of the things that I've been trying out is the use of buy now buttons on my Myspace account and other social networks that accept them as you can link to your own products if you have a paid subscription to place your own content files in the Ejunkie marketplace for sale, if you have a paypal account then you can get paid from any sales or affiliate sales that you achieve from your promotions.
There are lots of digital products to promote on Ejunkie, different topics and niches can be found, so if you have a collection of niche websites or blogs, then it's best to find relevant products that fit each one, this is also something that I am testing out and it's good seeing what many different ebooks and stuff are on there.
Ejunkie is an affordable option if you are selling your own digital products, starting at $5 a month, but if you fancy just using the site for affiliate promotions then you pay nothing. So it's something to think about when looking for possible alternatives to earn online.