Ooh, I thought of another one. Go to the future and get convincing special effects mannequins (movies now can have convincing corpses, they'll be even better in the future) of JFK, Lincoln, Martin Luther King, Gandhi, and various other people who were murdered. Do the same for notable historical figures who died of diseases we can now cure. If it's more than 150 years ago, I'll first have to go back in time to photograph them.
I'll go save all these historical figures and replace their bodies with the futuristic fake corpses. I'll introduce them to the modern world, showing them videos about all the history they've missed.
Also, I'd want to save important historical documents just before they were destroyed. For example, I'd save books from the libraries at Alexandria and Baghdad, which were destroyed by Roman and Mongol invaders respectively. These massive repositories of ancient knowledge might not have anything new, but they'd certainly be fascinating to translate.
I'd see if I could unlock the secrets of the still untranslated Voynich Manuscript, revealing the translation to the present so I don't change the past.