While thinking about this theme, I went back to look at some of my older pieces. Boy, there is a lot of sepia in my work. Almost all the monochrome ones seem to be in the sepia shades of tan, brown, rust and cream.
With the exception of the damselfly, this was all done with Photoshop brushes.
I downloaded a sepia palette from Adobe Kuler, and except for the green, I used only the five colors of the palette.