Let's talk specifically about Web content writers today, and the rights they give up when they sell their work.
In many cases, when a client purchases Web content from you, their primary objective is to target search terms for traffic or online readers. Most have no use for your content beyond their websites or blogs, leaving potential non-competing reprint markets available as an additional income stream for you (there are exceptions of course, such as a magazine which may print articles in hard copy as well as on their website).
Let's get one thing clear up front - if you've ghostwritten something as a work-for-hire, you've generally given up the full copyright to the work, so holding onto additional rights isn't an option. But what about bylined projects? Should you hold onto print rights and try to resell the content to offline clients?
It isn't something that I do often, but it can be an excellent way to earn some extra money, as well as a way for your initial client to save some money. Most clients ordering bylined Web content really don't need full rights. It just sounds good to them. Exclusive Web rights are what they really need in order to rank well in the search engines without worrying about duplicate content.
But sometimes other markets exist that don't directly compete. For example, a health writer might put together a piece on the health dangers of of pesticide use on common foods. It's published on the client's website. The writer may also be able to re-sell non-exclusive, print-only rights to their local newspaper if those pesticides are heavily used in their area. The markets are non-competing, but the content could be relevant to both an online and offline audience.
So should you pitch exclusive Web-only rights to clients instead of simply handing over full rights? I think it's a good idea if you have the inclination to actually pitch the piece elsewhere (and keep in mind - you may not want to now, but may wish you could down the road). I've found with bylined work that when you really explain the rights in relation to their needs, and offer a discount if you sell limited rights, clients are usually willing to work with you, and you can earn more from your initial Web writing in the process.
Do you hold onto print rights when possible? Do you actually pitch them to print publications? What has your experience been in negotiating rights with Web content clients?