Here are some useful links that tackle programming guidelines on C# and VB.NET.

VB.NET Coding Guidelines by Cory Smith
http://addressof.com/blog/articles/CodingGuidelines.aspx

VB.NEt Coding Guidelines by Daniel Moth
http://www.danielmoth.com/Blog/2004/09/vb-rules-net-way.html

VB.NET Coding Guidelines by GotDotNet.com
http://www.gotdotnet.com/team/vb/VBSampleGuidelines.htm

C# Coding Guidelines by Brad Adams
http://blogs.msdn.com/brada/articles/361363.aspx

C# Coding Guidelines by Joval Lowy
http://www.idesign.net/idesign/download/IDesign%20CSharp%20Coding%20Standard.zip

C# Coding Guidelines by Salman Ahmned
http://www.csharpfriends.com/Articles/getArticle.aspx?articleID=336

C# Coding Guidelines by Vic Hartog and Dennis Doomen
http://www.tiobe.com/standards/gemrcsharpcs.pdf

C# Coding Guidelines by Lance Hunt
http://home.comcast.net/~lancehunt/CSharp_Coding_Standards.pdf

C# Coding Guidelines by Vizualize.uk.com
http://www.visualize.uk.com/resources/asp-net-standards.asp

C# Coding Guidelines by Koen Muilwijk
http://www.students.cs.uu.nl/people/pmuilwij/coding/Coding%20guidelines.html

C# Architechture Design Guidelines from icsharpcode
http://www.icsharpcode.net/TechNotes/

C# Coding Guidelines by Mark Wagner
http://blogs.crsw.com/mark/category/45.aspx

Microsoft: Secure Coding Guidelines for the .NET Framework
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnnetsec/html/seccodeguide.asp

Microsoft: Secure ADO.NET Coding Guidelines
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconsecureadonetcodingguidelines.asp

Microsoft: Naming Convention Guidelines
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/cpconnamingguidelines.asp

Microsoft: Design Guidelines for Class Library Developers
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/cpconNETFrameworkDesignGuidelines.asp

Microsoft: Webcast on Modern Application Design and Concepts
http://www.microsoft.com/events/series/modernsoftdev.mspx

Microsoft: Patterns and Practices
http://www.msdn.microsoft.com/practices/GetStarted/

Set of Coding Standards from SSW
http://www.ssw.com.au/SSW/Standards/Default.aspx

.NET Programming Standards and Naming Conventions from IrritatedVowel
URL:http://www.irritatedvowel.com/Programming/Standards.aspx

Coding Standards for Visual Studio .NET By Dan Petit
http://www.flexisoftsolutions.com/NewsPressReleases/CodingStandardsWhitepaper.aspx

Hungarian for .NET Programs By Paul Yao and David Durant
http://www.paulyao.com/cfbook/AppA_HungarianForDotNETPrograms.pdf

Mono Coding Guidelines
http://www.mono-project.com/Coding_Guidelines

T-SQL Coding Standards
http://msdn.microsoft.com/sql/default.aspx?pull=/library/en-us/dnsqlpro04/html/sp04l9.asp