TreeThing is a simple program that is used to automatically generate forests which can then be exported in to your favourite paint program to use in your mapping.
It is written in Java and requires you to have JVM (Java Virtual Machine) installed to run it.
Here's an image to show a typical workflow...
And here is a PDF tutorial of how to use it...
TreeThing is free to use but I would ask that you credit me if you use it and if possible link to this thread so that others might find it.
Edit: Latest version - 0.9
1) UI update. Tried to make it a little more user-friendly by making most of the common functions more apparent. Most of the important features should be tooltipped - detailed tooltips are on by default but once you know the functions you can turn them to basic tooltips or off altogether in the options menu.
2) Added an option to randomly add some light shades of grey to the mask layer. This can be useful in post imagine by using the masks as a multiply layer to add variation. On by default.
3) Added a Link Brushes option in the options menu (or CTRL+L) to hold the current ratio between Brush 1 and Brush 2. Can save valuable seconds when resizing.
4) Added a Viewport Padding variable in the bottom menu (in Advanced) to adjust the free space surrounding a forest. This has no effect when a template is loaded.
5) Added the option to view your loaded template. Located in the View menu.
6) Various bug fixes and improvements.
Previous version - 0.81
1) It is now possible to save and load settings through an option in the File menu. Also, the current settings can be saved whenever the program is exited and these will be automatically loaded up the next time the program is run.
2) Added an option to utilise the greyscale of a template for brush positioning. This option is availble through the "Brush Weight" section of the parameter menu when a template is loaded. Obviously this needs a template tailored to greyscale.
3) Lost all memory of what was in previous versions so cannot say exactly what else is new.
Previous version - 0.75 - fixed
1) Changed the way the program handles shadows.
2) Added an option to adjust the positioning of shadows due to the way shadows are now handled.
3) UI updates.
4) Uploaded a fixed version that include the missing directory. :$