Over the years I've amassed a large number of these number line graphs, of different types, and thought I'd throw them up on the blog for the one or two other math teachers who might stumble across this and want them. They are in a PowerPoint format, because I found that working with shapes and lines in PowerPoint was easier than any other program I had. If you're interested, here's a file containing them.
They are just a series of shape objects, which I alter by adjusting their size or orientation. Once I have the graph I want, then I select all the objects, copy them, and paste them as a picture, which I can use in PowerPoint or Word.
One thing I am still looking for is a good source of creating two dimensional graphs. If you know of something, post it in the comments below.