How do I add data to the maps app introduced in iOS 6?
The previous answer works if Yelp is available in your country. Here's an alternative for the rest of us:

How to add a location or business to iOS 6 Maps

If an important location is missing in iOS 6 Maps you can use this process to suggest it.


Launch Maps from the Home screen.
Tap the page curl at the bottom right.
Tap the text that says Report a Problem above the Print button,
middle right.
Tap location is missing.
Tap Next.
Drag the purple pin to the right location on the map.
Enter the location information.
Tap Send.
Add any comments, if asked.


Apple will receive your suggested location, and if it meets their criteria, add it to the data base.