Irregardless of which sort of e-book you create, targeted to any niche – you will probably have some sort of revenue plan in mind, in the short or long term, and one great way to do so is affiliate programs.

Whether you're looking at selling physical products, such as printed materials, cds, or other types of merchandise or other info products, you'll be able to find them in places like http://www.paydotcom.com, http://www.clickbank.com, http://www.cj.com, and http://www.linkshare.com.

Once you've chosen the affiliate programs that matches up with your product, and niche best, you'll want to plan how to use them – one long term option is to create a mailing list and create an e-course around the affiliate links, promoting at least one per lesson. Your mini e-book could then be the 'gift' you offer for signing up to this e-c0urse.

Another good form of e-book is one that allows you to create a product from a transcript – these e-books are usually interview transcripts with popular or experts in the chosen niche. These e-books do very well when paired with affiliate offers from the expert themselves – and its usually win – win for your 'expert' – because, obviously, you'll be supporting their projects and offering their products as affiliate links. Its not the only reason you can offer to interview experts, but you'll have one more reason to approach them, with the right slant.
Transcripted interviews also provide another way to promote another info product, that pairs well with transcript mini e-books – audio recordings.

Once the momentum of your mini e-book distribution picks up, you'll find more and more people making purchases through your affiliate link – which, in the long term makes them very satisfying ways to create and maintain a passive income.