Millennials can do anything.
Not outright, but they can figure it out. It's an advantage of growing up with Google and so many other readily available tools. This is the day of the free Ivy League education, YouTube video's showing how to do millions of tasks, a near endless supply of helpful technologies, sites dedicated to hacking life's problems, and professionals angling to show their capabilities to the world by giving it away on a blog.
This attitude of heightened ability is a mentality more than a qualification. Millennials are not MacGyver's walking around (and that reference will be lost on most of them). They don't necessarily know the skills, they just know they can figure out how to do it, and quickly. It's partly why some tech CEO's publicly state that they hire young people because they're smarter.
Case in point, in 2009 I realized I needed a simple mobile app, so I asked an intern if he had ever made one. He had not, but I assured him that he could and asked him to look into it. A week later he came back having found a free service that allowed him to do so. With a bit more instruction on what I wanted he had a working prototype a few days later.
Nowadays, even your mildly-motivated millennial can do a host of tasks that a decade ago required years of training and technical skills. Here's a sample list of things I have done recently with links to the tools I used to do it:
This is seriously just a taste--I know I'll think of 10 more things I can do in the next day. Anything I couldn't do, I'd just Google, "how to free NAME OF TASK" and start digging.
I've realized that this list of competencies, while not extraordinary to any millennial, makes some from older generations swoon a bit. Not that they're lacking these skills--many can do some or all of them too--it's just not as common as with millennials. I've trained dozens of older colleagues how to do many of these tasks; what matters most is one's mindset--a belief that they can do it because the info you need is most likely "out there". So, my encouragement is to understand that, yes, millennials are quite skilled at doing lots of business relevant tasks, and that with a mindset stripped of limits and a teachable spirit you can too.
Back to millennials.
Just because they can do these things doesn't mean they can do them in a way to help your business as an employee or volunteer. It's vital that you guide their productivity prowess by providing a vision for an end goal and identify clear success metrics. You also need to show them samples of other work (either your own or stuff you like) to help them capture the desired voice. Also, be prepared to go through many rounds of editing and proofreading.
Once you've begun to "dance" with millennials allowing them to create for you, it get's easier and you'll find that your investment to set them loose is well worth it in the long run and that they, in fact, just might accomplish anything they set their mind to.