Scott Mitchell has put together an awesome tutorial on building and using 3-tiered date architecture with ASP.Net 2.0
It's available here
The flow of the tutorial is excellent, you can also download the tutorials in pdf format.
C# Tutorial in PDF format is available at http://www.asp.net/learn/dataaccess/datatutorials1_10cs.zip and http://www.asp.net/learn/dataaccess/datatutorials11_15cs.zip
VB.Net Tutorial in PDF format is available at http://www.asp.net/learn/dataaccess/datatutorials1_10vb.zip and http://www.asp.net/learn/dataaccess/datatutorials11_15vb.zip
If you want to kick start directly to a specific topic, I have listed down the different topics and the corresponding links for tutorial and source code for both C# and VB.Net.
Introduction
1. Creating a Data Access Layer
View this tutorial at C# VB.Net
Download source code: C# VB.Net
2. Creating a Business Logic LayerView this tutorial at C# VB.Net
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3. Master Pages and Site Navigation
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Basic Reporting
1. Displaying Data With the ObjectDataSource
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2. Declarative Parameters
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3. Programmatically Setting the ObjectDataSource's Parameter Values
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Master/Detail Reporting
1. Master/Detail Filtering With a DropDownList
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2. Master/Detail Filtering With Two DropDownLists
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3. Master/Detail Filtering Across Two Pages
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4. Master/Detail Using a Selectable Master GridView with a Details DetailView
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Custom formatting
1. Custom Formatting Based Upon Data
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2. Using TemplateFields in the GridView Control
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3. Using TemplateFields in the DetailsView Control
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4. Using the FormView's Templates
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5. Displaying Summary Information in the GridView's Footer
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Download source code: C# VB.Net
Scott Mitchell blogs here
Excellent work Scott, the tutorial is very usefull and interesting as well.