Answer:
The lunch destination of choice for teenagers and hospital employees.
Some adults still use these to count.
What gets broken without being held?
A mechanism to discover who is following you.
What comes one time in today, three times in tomorrow and never in the future?
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.