Benefits and Advantages

Software:
Software with resell rights have an advantage in that they have a high perceived value to the consumer. 
What this means is that consumers who buy software value the software format and are willing to pay a higher price then they would with other products.

Ebooks:
The advantage of ebooks is that they fulfill the need of the consumer for instant gratification.  What this means is that ebooks have an advantage when it comes to receiving an information product from traditional books.  The consumer orders the ebook and receives it right away without waiting for physical shipping that they might incur with traditional books.  The other advantage of ebooks is that they are convenient, highly portable and can be disseminated anywhere.  This is great for the consumer as they carry the same value as traditional books without the hassles.

Audio CDs:
The advantage of audiobooks and audio CDs is that like software and DVDs they carry a high perceived value in the eyes of the consumer.  Because of this audio CDs are easy to sell and profit from with the proper target market.  The other benefit of audio CDs is that the interface is simple and straight forward making it accessible to most people.  There are no compatibility issues that you might run across with software.

DVDs:
DVDs offer a great opportunity as a resell product because it has very high perceived value to consumers as well as high accessibility. Most middle income households now have DVD players and the reason they have DVD players is so they can buy and watch DVDs. People with DVD players are looking for you to provide them with DVDs that they can watch.