This post is not meant as a how-to guide; you can find those elsewhere. The main resource I used was Rain Gardens: Sustainable Landscaping for a Beautiful Yard and a Healthy World by Steiner and Domm. It has a Midwest focus, but I found it informative and inspiring. For Virginia specific info, see this page from the VA Dept. of Forestry and links therein, a rain garden guide for northern Virginia, plant recommendations from the VA Cooperative Extension, and various other online resources.
On to the fun part, pictures! These are clickable for larger versions. (Please excuse the blue tarp in most of the pictures. It is covering our generator, which is waiting for installation.)
We used a hose to decide on the location and shape of the garden, then marked the edges with spray paint before digging.
This part of the yard was solid clay, so it had to be replaced with well drained soil. We rented a miniature backhoe to dig out the clay. Here is the final hole.
We used the extra clay to re-contour our side yard and make it more even.