Recently, Wolfram Alpha LLC dropped the official WolframAlpha app into the market. It is one of my favorite services and I purchased it ($1.99) as soon as it came out. For those not familiar, this is a clip from the "about" page of WolframAlpha to give you some idea of what this is all about:
Wolfram|Alpha's long-term goal is to make all systematic knowledge immediately computable and accessible to everyone. We aim to collect and curate all objective data; implement every known model, method, and algorithm; and make it possible to compute whatever can be computed about anything.