Just realizing a couple uses for Twitter:
(I am @unclefishbits)
The OR national guard may or may not use it to contact their guard (among other ways, of course)
basketball teams are able to communicate about where practice will be held. Or the friend with a view of the courts can say when the courts look free.
Chess in the park to let the group know where and when to meet.
It really depends on your interests, and then it becomes useful. In SF there are people that organize or tweet about food… specials, treats, free stuff. Or others about farmer’s markets and what is REALLY good. I follow a whole bunch of hotel people… we talk about the biz, ask each other questions, etc.
There is a great wine contingent on there… you can compare tasting notes, talk about GREAT specials at different places, find out about hidden gems, etc.
or it can help a revolution in Iran.