Something like this would be one way to approach things:
The Xaml:

<Window.Resources>
        <!-- Markers Point -->
        <DataTemplate DataType="{x:Type igChart:MarkerTemplate}">
            <Ellipse Stroke="{Binding Path=Stroke}" 
                     Fill="{Binding Path=Fill}" 
                     Width="12" Height="12"
                     ToolTip="{Binding Path=ToolTip}"/>
        </DataTemplate>

        <local:TestData x:Key="data" />

        <DataTemplate x:Key="chartTooltip1">
            <StackPanel>
                <StackPanel Orientation="Horizontal" >
                    <TextBlock Text="Label: "/>
                    <TextBlock Text="{Binding Label}" Foreground="Blue"/>
                </StackPanel>
                <StackPanel Orientation="Horizontal" >
                    <TextBlock Text="Value: "/>
                    <TextBlock Text="{Binding Value}" Foreground="Blue"/>
                </StackPanel>
            </StackPanel>
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <igChart:XamChart>
            <igChart:XamChart.Series>
                <igChart:Series ChartType="Line" 
                                DataSource="{StaticResource data}"
                                DataMapping="Label = Label; Value = Value; Tooltip = Tooltip">

                    <igChart:Series.Marker>
                        <igChart:Marker UseDataTemplate="True" 
                                        Foreground="#FF686868" 
                                        FontFamily="Verdana" 
                                        FontSize="14" LabelDistance="5"/>
                    </igChart:Series.Marker>
                </igChart:Series>
            </igChart:XamChart.Series>
        </igChart:XamChart>
    </Grid>

And the code behind:

public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();

            Application.Current
                .Resources.Add("chartTooltip1",
                Resources["chartTooltip1"]);
        }
    }

    public class TestData
        : ObservableCollection<TestDataItem>
    {
        public TestData()
        {
            this.Add(new TestDataItem()
                         {
                             Label = "1",
                             Value = 1
                         });
            this.Add(new TestDataItem()
                         {
                             Label = "2",
                             Value = 2
                         });
            this.Add(new TestDataItem()
                         {
                             Label = "3",
                             Value = 3
                         });
            this.Add(new TestDataItem()
                         {
                             Label = "4",
                             Value = 4
                         });
            this.Add(new TestDataItem()
                         {
                             Label = "5",
                             Value = 5
                         });
        }
    }

    public class TestDataItem
    {
        private DataTemplate Template { get; set; }
        public string Label { get; set; }
        public double Value { get; set; }
        public object Tooltip
        {
            get
            {
                if (Template == null)
                {
                    Template =
                        Application.Current
                        .Resources["chartTooltip1"]
                        as DataTemplate;
                }

                if (Template != null)
                {
                    return new ContentControl()
                    {
                        Content = this,
                        ContentTemplate = Template
                    };
                }
                else
                {
                    return "Label: " + Label + 
                        ", Value: " + 
                        Value.ToString();
                }
            }
        }
    }

Let me know if this helps!

-Graham

That is what this does, unless I'm misunderstanding what you are asking for.

-Graham

I don't think this does exactly what I want. Let's say for example:

When my mouse is over DataPoint[0] I want the label to display DataPoint[0]. Label, DataPoint[0]. Value

I don't want to display all the DataPoint's just the one my mouse it over.