SharePoint Designer

Microsoft SharePoint Designer 2010 is a Web and application design program used to build and customize SharePoint sites and applications. With SharePoint Designer 2010, you can create data-rich pages, build powerful workflow-enabled solutions, and design the look and feel of your site. The sites you create may range from small project management sites to dashboard-driven portal solutions for the enterprise.

See: http://office.microsoft.com/en-gb/sharepoint-designer-help/introducing-sharepoint-designer-2010-HA101782482.aspx?CTT=1