Find a cross-platform mobile SDK. Use one code base to develop apps for Android, iOS and more.
What language do you prefer?
Want to make a mobile app without programming? Then try one of these.
Also, there are web services that can be used by all mobile app developers.
Are you a developer but need to find a mobile designer? Maybe try Scoutize.com (no affiliation, just cool).
Designing Mobile Interfaces by Steven Hoober and Eric Berkman
Make cross-platform mobile...