There are many reasons which make ebooks great products.

To start with the biggest and most powerful reason for this is that information is king!

There are ebooks on so many topics you are sure to find on on any niche market you find interesting and would like in which to sell to.

They are also relatively cheap so there are many times people that would not spend a lot of money on an item that they are just curious about that will then end up being a buyer not a looker.

Further more, you cannot beat the convenience of delivering an ebook.  You don't have to ship it, it doesn't cost anything to get it to its new owner and they in many cases can get what they have paid for immediately.  Which in my experience turns into some pretty serious customer satisfaction.

And another great thing is that they are easily made so if you have any knowledge on a certain subject you can be self published in minutes and start making money from your own ebook product on eBay and other sites within a few days!