Matus Goljer (Fuco1) has another excellent suggestion in his latest blog posting. A recent project required a large list of tasks to be completed, which he tracked with Org mode checkboxes. The problem was that it was visually confusing and hard to see clearly the items that still needed to be done. Fuco1 solved that problem by arranging for the completed checkbox items to be displayed in the org-headline-done face. With his theme, that’s a grayed out rendering and easily distinguished from an uncompleted task.
That’s pretty nice but I’m so far behind I didn’t even know about the org-headline-done face or how to use it. Out of the box, Org will display completed headlines (DONE, etc.) in that face if you set org-fontify-done-headline to t. I’d never heard of that so I manually set org-fontify-done-headline to t in the minibuffer to try it out. I’m pretty happy with the result and will probably make it permanent by moving it into my init.el.
Even if you don’t have long task lists, you might like turning the feature on to make completed TODO items stand out. It’s easy to try out temporarily by just turning it on from the minibuffer. If you like it, you can make it permanent.