A lot of hardware and software hackers aren’t all that keen on documentation. The problem is, if you don’t document, it is harder for people to replicate or build on your work. If you aren’t happy writing, keep the old adage in mind: a picture is worth a thousand words.
With a digital design, a timing diagram is often a key piece of documentation. WaveMe is a free Windows program that makes it easy to create good-looking timing diagrams. You can run the software on other platforms via Wine.
The software can handle signals and busses. It also allows rulers, labels, and other items you’d expect in a tool like this. Of course, you could draw diagrams using any drawing tool, but using something that specifically knows about timing diagrams makes it a lot easier.
If you prefer a more text-based approach, check out Wavedrom (or one of the other similar fonts like XWave, mentioned in the same post). If you’d rather make real waves instead of pictures, you could try making a waveform generator.