SharePoint Designer 2010 is the tool for building powerful applications on top of SharePoint without coding. It allows users to create lists, pages, workflows, and connect to external data sources. Some key improvements in SharePoint Designer 2010 include a new user interface with ribbons and summaries, the ability to directly create and customize content types and site assets, and more options for restricting access at the web application and site collection levels. Workflows, external data connectivity, and manipulating list views are some of the main capabilities demonstrated.