Headshots aren't just for actors. According to Wikipedia, "A head shot is a modern portrait for todays branding needs, where the focus of the photograph is the personality inside the person captured." There are many reasons for needing a headshot.
The business headshot can be used everywhere from company publications such as annual reports to information pages on the company's website. For the individual, they can be used for social media networks such as LinkedIn and Facebook. The picture you choose for social media sites is the first impression people will get of you. Snapshots taken by family or friends will not appear professional.
Other uses for a business headshot might be marketing material such as flyers, calendars, and business cards. Headshots can can also be included in press material such as press releases.
As for actors, headshots are still very relevant to getting your next job. Your headshot is your visual introduction to the casting director. It should be an accurate representation of what you look like so he or she can see you are the best person for the role.
No matter what, a good headshot will move you toward your goals.
