Over at the Microsoft MSDN site there is an excellent set of ASP.NET 2.0 tutorials written by Scott Mitchell (of 4GuysFromRolla fame). These very useful and up-to-date (June 2006) tutorials walk you through creating a Data Access Layer (DAL), a Business Logic Layer (BLL), using Master pages (one of the great new features in ASP.NET 2.0) and wiring up UI elements to business objects. Each includes downloadable source code.
The series consists of:
Tutorial 1: Creating a Data Access Layer
Tutorial 2: Creating a Business Logic Layer
Tutorial 3: Master Pages and Site Navigation
Tutorial 4: Displaying Data with the ObjectDataSource
Tutorial 5: Declarative Parameters
Tutorial 6: Programmatically Setting the ObjectDataSource’s Parameter Values
Tutorial 7: Master/Detail Filtering With a DropDownList
Tutorial 8: Master/Detail Filtering With Two DropDownLists
Tutorial 9: Master/Detail Filtering Across Two Pages.
Tutorial 10: Master/Detail Using a Selectable Master GridView with a Details DetailView