Twitter is a program that lets you tell the world what you're doing or thinking at any given time. It is largely inane, and people will often make an announcement about things that should not be documented.
However, mad genius Jhonen Vasquez has figured out how to make 140 character updates worth following. Here's a sample:
Bought a 12 pack of toilet paper. Danced around while the woman at the checkout rang me up. Leaned in and said "This is just for today."