Ken has blogged about EDSITEment previously, and how terrific a resource it is, so I would like to focus here on its monthly interactive calendar.
EDSITEment's monthly calendar is annotated with listings of historical events that occurred on that date. For example, for January, LBJ announced his "Great Society" programs in a State of the Union address in 1965 on January 4; the Supreme Court decided Roe v. Wade in 1973 on January 22; and the Apollo Theatre opened in Harlem in 1934 on January 26. (Sadly, nothing of note happened on my birthday, January 25!) Clicking on an event takes you to a fully-formed lesson with resources.
Bookmark this calendar and follow them (@EDSITEment) on Twitter! Their topics are engaging so you will definitely find several great prepared lessons here.