Yes it is, my friend! And it should be in your career plan too. That little line that states “Other duties as required” or “Other duties as requested” shows that whatever the boss-man or boss-lady asks is within your scope. (By the way, please do not add this line to your resume, as it adds no value at all.)
But, there should be a bigger and more exciting reason for you to want to embrace special projects, and that is to boost your resume and your knowledge!
Your resume and interview are not just about your job description, but also should encompass the many positive contributions you have made to your employer. Some of those would be the above and beyond type projects which allow you the opportunity to utilize additional knowledge of other areas of a company. For instance, if you are in information technology, but assisted on an implementation to increase marketing visibility, the project broadens your scope of knowledge, thereby making you a more appealing candidate to a hiring organization.
Think about it: do you really want to pass on the “other duties” that an employer will like? That includes your own employer, who may promote you when the project succeeds!