ApplicationController.cs

public class ApplicationController : Controller
{
  //...
  protected override void Initialize(System.Web.Routing.RequestContext requestContext)
  {
      log4net.GlobalContext.Properties["requestid"] = Guid.NewGuid();
      log4net.GlobalContext.Properties["email"] = CurrentUser.Email;
      log4net.GlobalContext.Properties["customername"] = CurrentCustomer.Name;
      log4net.GlobalContext.Properties["url"] = requestContext.HttpContext.Request.Url.ToString();
  }
  //...
}

gistfile1.xml

<log4net>
  <appender name="AdoNetAppender" type="log4net.Appender.AdoNetAppender">
    <bufferSize value="10" />
    <connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
    <connectionString value="Data Source=somedatabaseserver;Initial Catalog=ZPE;Persist Security Info=True;User ID=sauceybastard;Password=jesusjuiceX12345;timeout=120" />


    <!-- THIS IS ALSO IMPORTANT!!! --->
    <commandText value="INSERT INTO Log ([Date],[Thread],[Level],[Logger],[Message],[Exception],[RequestId],[Email],[CustomerName],[Url]) VALUES (@log_date, @thread, @log_level, @logger, @message, @exception, @requestid, @email, @customername, @url)" />
    <!-- CARRY ON! -->


    <parameter>
      <parameterName value="@log_date" />
      <dbType value="DateTime" />
      <layout type="log4net.Layout.RawTimeStampLayout" />
    </parameter>
    <parameter>
      <parameterName value="@thread" />
      <dbType value="String" />
      <size value="255" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%thread" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@log_level" />
      <dbType value="String" />
      <size value="50" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%level" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@logger" />
      <dbType value="String" />
      <size value="255" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%logger" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@message" />
      <dbType value="String" />
      <size value="4000" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%message" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@exception" />
      <dbType value="String" />
      <size value="2000" />
      <layout type="log4net.Layout.ExceptionLayout" />
    </parameter>

    <!-- BELOW IS THE INTERESTING STUFF! -->

    <parameter>
      <parameterName value="@requestid" />
      <dbType value="Guid" />
      <layout type="log4net.Layout.RawPropertyLayout">
        <key value="requestid" />
        <conversionPattern value="%property{requestid}" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@email" />
      <dbType value="String"/>
      <size value="255"/>
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%property{email}" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@customername" />
      <dbType value="String"/>
      <size value="500"/>
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%property{customername}" />
      </layout>
    </parameter>
    <parameter>
      <parameterName value="@url" />
      <dbType value="String"/>
      <size value="2048"/>
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%property{url}" />
      </layout>
    </parameter>
  </appender>
  <root>
    <level value="all" />
    <appender-ref ref="AdoNetAppender" />
  </root>
</log4net>

more_loggin.cs

// Copy and paste is easy!
var message = String.Format("/User/Profile/{0} edited by user {1} for customer {2}",userid,email,customername);
Logger.Info(message);

string_formatting.cs

// I'm so clever!
var message = String.Format("/User/Edit/{0} edited by user {1} for customer {2}",userid,email,customername);
Logger.Info(message);