Mahalo.com has an interesting history. They started as a search engine, then turned into some sort of a Q&A site and now Mahalo is focused on creating mobile apps for the iPhone, iPad and Android.
Most apps from Mahalo are focused around learning music instruments, video game walkthroughs, cheatsheets and software tutorials (like GaragaBand and Final Cut Pro X). The apps have step-by-step video lessons accompanied by exercises and some of these apps are actually very good.
The apps cost anywhere between $1.99 and $4.99 per app but they have recently slashed the prices and you can now have them all for free. Whether you want to learn the guitar or master the piano or just need to know how to complete that level in Cut the Rope game, there’s an app for you.