Enable the TrackBallInfo to be vertically aligned (e.g. the bottom of the chart).

Implement Waterfall series type (http://en.wikipedia.org/wiki/Waterfall_chart).

Make the StepLineSeries being able to plot a 'step' for a single point. Currently the StepLine series does not support drawing a single data point when it is in the beginning or the end of the ItemsSource. 

Add auto-range ability for the numeric axes that adjusts its range in accordance to the visible/zoomed data to show the data more clearly

When the CartesianPlotBand annotation is bound to the vertical axis its 'From' value doesn't align with the axis.
This changes when resizing.

When a System.Windows.Interactivity.EventTrigger is attached to a ChartTrackBallBehavior a XamlParseException is thrown. A possible work-around for this would be to set the CommandParameter to be the parent collection of the behavior and not the behavior itself.

ChartDataSource control should perform the sampling operation asynchronously in a background thread so that it is not blocking the UI thread.

When the values of the data points have great values and the axis has a very small manual range, the Path element does not render correctly and is at times not visible at all.

Workaround:
A possible way to resolve this is to use the Direct2DRenderOptions. The different render modes use a completely different rendering logic.
<telerik:LineSeries.RenderOptions>
 <telerik:Direct2DRenderOptions />
</telerik:LineSeries.RenderOptions>

Users should be able to create custom financial indicators.

Add mechanism in RadCartesianChart to change the axis origin position. Currently, you can position it only top, left, right or bottom. Add an option to position the axis at an arbitrary position on the opposite axis. For example, to position the horizontal axis in the middle of the vertical axis or at value lets say 3.

Add support for Tornado Chart. You can check this link for more information.

Sample Tornado Chart:

Add support for drill-down functionality.

Add ScatterRangeSeries visualization, similar to RangeSeries.

Add mechanism for getting the layout slot of the axis

The stroke property of the PaletteEntry is not respected.

Add a mechanism that allows the chart to process only the data within the viewport. This should improve the memory footprint and the performance of the chart in scenarios with big number of data points.

The series are not rendered as expected when using Direct2DRenderOptions and hiding labels (by setting the LabelInterval, SmartLabelsMode or via a different approach)

Convert ZIndex property of the series to dependency property