Qlikview is one of the easiest and flexible Business Intelligence visualization tool I’ve used for my BI development in the last few years. It is simple, but have powerful scripting language that allow you to customize it in many ways. What is also very promising is that Qlik.com continue to innovate and extent their platform, so we should expect to see on-going improvement from the product.
For those of you who maybe new to Qlikview, here is a really good video tutorial that will jump-start your adventure into BI visualization development.
For your reference, a live demo is also available: Data Visualization Live Demo