YesGnome, LLC has Star Trek Trexels (iTunes Link) for the iPhone, iPod Touch, and iPad in the iTunes App Store for FREE (regularly $2.99) for a limited time.

The USS Valiant has been destroyed by an unknown attacker, and Starfleet has chosen YOU to continue its mission deep within a mysterious area of space known as the Trexelian Expanse. Build your ship, choose your crew, learn the fate of the Valiant, and explore the Expanse in the name of the Federation.