Today's WORD is an e-mail service Tokio Morishima is subscribed to. Once a day, every day, the Daily Mail Magazine sends a short saying or quote to subscribers, along with either an explanation of the meaning or the person who originally said it.
A Today's WORD exists for every day Tokio checks his e-mail in a Placebo report. In *05 MISOGI, a number of Today's WORDs all come in at once. Some Today's WORDs seem to have relevance to the plot or present events, though many others seem random.