It wrecks aesthetics but it's a necessary evil sometimes: The version number.
Oftentimes, it's fine to keep it out of the app entirely, or hide it in the Settings app. But sometimes, it's necessary for the user to access it, either to check the version he or she is using, or for QA or debugging.
Here are some creative ways I've put them into an app:
1. Shake the first screen to make it appear.
2. Show on the first screen, then fade it out after 10 seconds.
3. Show it on the first screen via an invisible button (or easter-egg-type touch gesture)