If there's one company in the world that is in the business of keeping people happy, it's Astraware. They're a UK-based development firm that excels in writing games for handheld devices. In the past, they've published games like Bejeweled 2, Cubis, and Zuma for Palm and Windows Mobile, and now they're entering the iPhone market with a splash.
GTS World Racing is an arcade-style racing game licensed from Pazzazz Games that, like Crash Bandicoot Nitro Kart 3D, uses the accelerometers in the iPhone / iPod touch for control. Tilting the iPhone left or right steers your car, tilting forward accelerates the car, and tilting back applies the brakes.
The game provides 64 different track layouts, so you're not likely to get bored going around the same track again and again. There are 16 different worldwide locations for backdrops, as well as three different car types and four different levels of difficulty (I hate to admit that I'm still stuck at the "Easy" level...). You can also play your own music in the background if you tire of the built-in soundtrack.
Update: GTS World Racing is now available here (click opens iTunes) for US$7.99
In the interest of full disclosure, the author has had a long-term reviewing relationship with Astraware.