This plugin is similar to (and is based on) Grid Maker plugin available here: http://paintdotnet.forumer.com/viewtopic.php?f=16&t=4879
I wrote Graph Maker to make it easy for me to analyze graphs (in Civilization IV) which don't have axes markings. Features include:
[*:1q5jwbi9]Specify the number of squares in the grid, not the size of each square. This allows you to accurately place grids on graphs where each unit doesn't correspond to a whole number of pixels. [*:1q5jwbi9]The grid is calculated based on the currently selected rectangle, not the whole image. [*:1q5jwbi9]You can have every 5th (or whatever number you choose) line be drawn in the secondary color, making it easier to figure out the exact value of a point on the graph.
You can download the plugin here: GraphMaker.zip
Unzip the dll into the Effects folder under your Paint.NET installation directory. The plugin will be found in the Effects menu, under the Render submenu.
Here is the source code: GraphMakerSrc.zip
Here is a screenshot of the plugin in use:
I wrote this for my own use, but if you have any suggestions for improvements, feel free to let me know.