NON-COMPETITION. The Author shall not prepare or be concerned in the preparation other than for the Publisher of any work which shall be an expansion or abridgment of the current Work, in whole or in part, or of a nature likely to affect prejudicially sales of the current Work. The Author will consult with Publisher before publishing or producing another work likely to affect prejudicially the sales of the Work herein contracted for.How long? Our initial concern about this provision -- besides the fact that it doesn't accurately define a competing work, and is written in a funky old-school contract writing style -- is how long the provision can be enforced. Since no time period is mentioned, we assume it's enforceable for the term (time period) of the agreement. We don't know what the term is, but it should be written somewhere in your agreement. In book contracts, it's typically for as long as the book remains in print (see our previous entry) or for the length of copyright. In either case, that's a long time. So, if you have the bargaining power, you might want to put a timer on this one -- for example, to preface the provision by saying, "For a period of one year, following publication of the Work, the Author shall not ....
What's competing? Our second concern is that it doesn't clearly define a competing work. It's no accident that this provision is vague. In the minds of some attorneys, ambiguity increases the breadth of coverage because it makes it possible to threaten and intimidate an author over any type (as long as it will "affect prejudicially sales") or size ("an expansion or abridgment") of work. An author with some bargaining power would want to limit this to a specific thing -- for example book-length works on the same specific topic. Also, if the contract contains a clause providing a right of first refusal for your next work (the publisher has first dibs on your next book), you should add language saying that if the publisher doesn't want to publish it, that your second book will not be considered a competing work.
Does your other stuff compete? Because the provision is so vague, we can't say whether the publisher will care about your other works and if so, what will the publisher do. If we were a betting blog, we would bet that the publisher probably won't care or do anything. First, they're probably aware that you're the expert on this particular subject and they're aware of your site and your freelance column, so they won't want to put a halt to this type of self-promotion -- it helps the book. Your one-off articles may or may not trigger friction. That depends on who is publishing them and where they are being published. One way to secure your position is to include a mention of the book in any of these efforts as that way you can make a reasonable argument that they are promotional not prejudicial.
Just sayin'. If you speak with one of the editors or publisher reps, you may want to discuss these concerns. The publisher may not change the contract (which will ultimately control what happens) but they may assure you that the provision is rarely enforced.
PS Feel free to send our contracts book to the company's legal counsel.