Having developed a few iPhone/iPad apps now there has been a few things that have tripped me up and created more work than necessary.
One of those is that small bugs in the program such as a bad link, misspelled words or game play tweaks like speeds and frequencies that you want to change after the app has been submitted usually require fixing the code and re-submitting the new binary which takes another week to get reviewed. Depending on the error it could delay the marketing push on the app and cost you a week of lost revenue.
The week long delay in fixing what can be trivial typo errors can be frustrating.
To counteract that it can be useful to move some of these settings to a plist file and update the values from a website. It can be as simple as putting a json/xml file on a web server somewhere and loading/parsing that file every time the app comes into the foreground.
This feature has become central to a few of my apps. allowing me to update the content of the app with fresh information, it has also allowed me to test various minor changes in some games in production, and allowed me to fix a link to include an iTunes affiliate link after it was published without one.
This merging of what makes native apps so great (speed, better controls etc) with what makes web apps great (always up to date, easy to deploy fixes, and tracking) is what I find most interesting about mobile apps.