I was googling for classic designs of herb gardens and came across GrowVeg.com. They've got a free trial (one that you don't have to fork over you credit card info for) so I decided to try it out.
The basic idea is that it provides a grid and a rather exhaustive list of vegetables, fruits and herbs (it also has info on growing each of these) that you drag & drop onto the garden area you've created. It's also got a crop rotation feature. Plus? You've got a record of what you've planted where each year. They also say that they will email you to remind you of planting dates.
Now, I did this by hand last year, but kept changing my mind & had to redraw the garden area each time as well as draw back in the stuff I wanted to keep (or I could have drawn in pencil. whoops).
I'm not sure that I'll covert to GrowVeg.com (the subscription is cheap at $25/year) but it's certainly something to keep in mind...