Beta Acid is a software development agency based in New York City. Their method one part Design Thinking, two parts Lean Startup, and a whole lot of battle scars. Quickly create rough, tactile prototypes to test in the real world. Evaluate with structured goals. Continually use data to analyze effectiveness of the product, improve with laser focus. Building software like a startup for companies of all sizes.
Tatar on Rails is just a group of people passionate about Ruby on Rails apps and customer experience. With developers/designers/QA from Russia, USA, Pakistan and Thailand, it looks like they can call themselves an international company. They focus on customer experience. Really care about timeline, budget and Management.
UX Mind designers specializing in interface design, UX / UI website design and mobile applications design. They work to make the complex things simple, unclear - logical, abstract - concrete, and as a result to organize effective interaction of users with your product.