As long as we’re dumping on religion:
With apparently impeccible credentials as an envoy from Rome, I have Pointius Pilate write out a full and detailed report on the execution of Jesus, have scribes make twenty copies, and have them stored somewhere where I know they’ll be undisturbed until the 21st century, then make sure they’re found in the present.
Assuming I cannot get an audience with the powers that be:
[ul]
[li]Pick up the cigars for the Confederate officer before Antietam[/li][li]Stop the courier delivering news of Ögedei’s death to the Mongol forces in Europe[/li][li]Throw some thermite and controlled demolition equipment into the WTC rubble[/li] [/ul]
No no no - Go foward in time, grab Pointius Pilate’s body, bring it back and place it in tomb. That’d screw with everyone’s head.
Interfere with Washington’s efforts to evacuate from Long Island after he got his ass handed to him. Thus ends the American Revolution.
Steal the trade goods from Peter Minuit.
Reinforce Harold of England, and give him tactical guidance against the Normans. Then shoot him.
Go forward in time to kill my grandson before he comes backward in time to kill me before my kids were born.
Obtain Patent #0001 for my time machine. (Because, really, what other patent number could a time machine have?) Then run around spoiling everyone’s fun with predictions of random accuracy.
Collect the most popular songs of the last 30 years and hand them out to Kenny Rogers, Englebert Humperdink and Confederate Railroad.
Re-edit the story of Onan so that the sin he committed was that he rolled over and went to sleep afterwards instead of listening to her talk about their relationship for an hour. Or that he didn’t go to sleep immediately. Depends on who you want to be a dick to.
Of all the famous murder mysteries in history, document all the ones where the murderer turned out to be some random psychotic who committed a pointless opportunity killing.