Memeware

Memeware is shareware with a chain letter option, meaning users can propagate it as an alternative to paying for it. A memeware license would be something like:

This book is memeware. You may reproduce or distribute this book only in complete and unmodified copies, only for non-commercial purposes, and only if you agree to this memeware license. If you find this book useless, you owe the author nothing. If you find it useful, you should do one or both of:

• Propagate copies of it (complete with this memeware license) to at least two people who find it useful and do not yet have a copy, and send the author some (not necessarily identifying) indication of who they are.

Pay the author however much the book is worth to you. If the amount ($5? 5¢? 0¢?) is much less than the effort of sending it, then add the amount to your next charitable donation and advise the author of the charity and the amount.

Memeware is used by copyright holders who care more about spreading particular memes than about finanical rewards, and is a form of open content inasmuch as it "explicitly allows the copying of the information". An example of memeware is the online reference hypertext Human Knowledge: Foundations and Limits.