Okay, this is what I have added to the existing chart tools that come with my main utilities.
Gantt Chart Maker

You can use it to show hours or days (dates). If you make Gantt charts on a regular basis, this might help. Settings for formatting are recorded so it may save a little time.
Add Custom Gridline

This allows you to add a gridline to line or scatter charts where you want it, to get around the default restrictions. With scatter charts, you have the option of adding a horizontal or vertical gridlines. You can show the value to the left (or below) the gridline. You can then make use of Excel's built-in formatting features if you want the gridline to stand out.
Axis Alignment

This was formerly called "Make X Axis Cross At Minimum Value". I can't remember the reasoning behind it but it did not seem to work when I tried it recently. Anyway, I added some functionality and hopefully it will come in useful, I think it is a little easier to understand and use than the default version of formatting for axis alignment.
I also made some improvements to Add Data LabelsFrom Range and Show Fonts Sheet.
The most recent version of the utilities can be downloaded here.