Behold--Batman the cereal!
The film was so big that it had not only one but two successful toy lines. The first one was by the small company Toy Biz, which also released other DC Comics characters in a separate line released concurrently with their Batman line. Ironically, the owner of the company was Ike Perlmutter, who now is the CEO of Marvel Entertainment.
The following year (1990), Kenner released The Dark Knight Collection, a larger line also based on the 1989 movie. Here are almost six minutes of commercials for the line.
I still have the Crime Attack Batman action figure from the line to this very day.
In addition to toys, you can always count on fast food restaurants to take part in blockbuster movie promotions. For Batman 1989, the fast food joint of choice was Taco Bell with these cool cups! Collect all four! Don't forget your cinnamon twists!
Finally, MTV held a "Steal The Batmobile" contest in 1989. Movie costar Robert Wuhl has all the details!
I'll bet you're now inspired to rush to Ebay and see if you can get any of this stuff cheap. Good luck!