Wolfram Alpha for iPhone packs big features and a big $50 pricetag
On the other hand, the app does the kind of high-level math that would make Texas Instruments weep. If you're a student or someone in a math-intensive technical field, it might rock your world. Integrals, derivatives, differential equations, and all of the other stuff I've forgotten from years of math classes? Look no further than Wolfram Alpha. It's more than just a graph generator and equation-solver, though. Wolfram Alpha offers data on everything from finances to books, movies and music, and it's often quicker than the equivalent Google Search.
Is it worth $50? That depends on what you intend to use it for, but it's certainly less expensive (and less bulky) than a graphing calculator.