a post on a blog, a tweet on Twitter, or an activity on Facebook to let friends know you are alive and well, or alive and troubled.
Hamlet - "I haven't seen a "heart-beat post" from Ophelia in a few days, I hope she's okay. I can't call her to find out, because, you know, it's complicated, but those heart-beat posts let me know she's thinking of me."

Horatio - "Yes, she's fine. I saw a 'heart-beat post' on her blog, the first one she's done in three days, about going to the river"
by Rocksandshoals November 24, 2009