void GetElementParameterInformation(Document document, Element element)
{
    // Format the prompt information string
    String prompt = "Show parameters in selected Element: \n\r";

    StringBuilder st = new StringBuilder();
    // iterate element's parameters
    foreach (Parameter para in element.Parameters)
    {
        st.AppendLine(GetParameterInformation(para, document));
    }

    // Give the user some information
    TaskDialog.Show("Revit", prompt + st.ToString());
}

String GetParameterInformation(Parameter para, Document document)
{
    string defName = para.Definition.Name + "\t : ";
    string defValue = string.Empty;
    // Use different method to get parameter data according to the storage type
    switch (para.StorageType)
    {
        case StorageType.Double:
            //covert the number into Metric
            defValue = para.AsValueString();
            break;
        case StorageType.ElementId:
            //find out the name of the element
            Autodesk.Revit.DB.ElementId id = para.AsElementId();
            if (id.IntegerValue >= 0)
            {
                defValue = document.GetElement(id).Name;
            }
            else
            {
                defValue = id.IntegerValue.ToString();
            }
            break;
        case StorageType.Integer:
            if (ParameterType.YesNo == para.Definition.ParameterType)
            {
                if (para.AsInteger() == 0)
                {
                    defValue = "False";
                }
                else
                {
                    defValue = "True";
                }
            }
            else
            {
                defValue = para.AsInteger().ToString();
            }
            break;
        case StorageType.String:
            defValue = para.AsString();
            break;
        default:
            defValue = "Unexposed parameter.";
            break;
    }

    return defName + defValue;
}

Private Sub GetElementParameterInformation(document As Document, element As Element)
    ' Format the prompt information string
    Dim prompt As [String] = "Show parameters in selected Element: " & vbLf & vbCr

    Dim st As New StringBuilder()
    ' iterate element's parameters
    For Each para As Parameter In element.Parameters
        st.AppendLine(GetParameterInformation(para, document))
    Next

    ' Give the user some information
    TaskDialog.Show("Revit", prompt + st.ToString())
End Sub

Private Function GetParameterInformation(para As Parameter, document As Document) As [String]
    Dim defName As String = para.Definition.Name + vbTab & " : "
    Dim defValue As String = String.Empty
    ' Use different method to get parameter data according to the storage type
    Select Case para.StorageType
        Case StorageType.[Double]
            'covert the number into Metric
            defValue = para.AsValueString()
            Exit Select
        Case StorageType.ElementId
            'find out the name of the element
            Dim id As Autodesk.Revit.DB.ElementId = para.AsElementId()
            If id.IntegerValue >= 0 Then
                defValue = document.GetElement(id).Name
            Else
                defValue = id.IntegerValue.ToString()
            End If
            Exit Select
        Case StorageType.[Integer]
            If ParameterType.YesNo = para.Definition.ParameterType Then
                If para.AsInteger() = 0 Then
                    defValue = "False"
                Else
                    defValue = "True"
                End If
            Else
                defValue = para.AsInteger().ToString()
            End If
            Exit Select
        Case StorageType.[String]
            defValue = para.AsString()
            Exit Select
        Case Else
            defValue = "Unexposed parameter."
            Exit Select
    End Select

    Return defName & defValue
End Function