A feature of Twitter is the hashmark listing, which makes it easy for viewers to keep track of certain topics.
Yesterday (Tuesday!) I received this helpful tweet: "Have you heard about #charitytuesday? Maybe it can help increase awareness of #BIDMC on twitter."
Here's an article that describes this more fully, citing this one by John Carnell, which I offer here to be helpful to other non-profits who might either be on Twitter already or might be wondering why it would be useful to be on it.