I asked this question in the Wisdom of the Crowd:

Will you buy a wristband to have an emergency contact number?

Here are the responses: (53 Votes)

62 % - I will use it for older people and young kids.
21 % - I will use it for everyone, in case they get lost of injured.
17 % - I will not use it.

See the pie chart at:
http://www.tklcloud.com/Crowd2/chart.aspx?ID=2629

CLick here to vote on the current issues:
https://tklcloud.com/Crowd2/active_issue.aspx