I came across this really simple button maker today:

• http://www.buttonator.com/

You pick the button style, add text, set a few options then right-click & save. If you're interested they also have extra options you can get by paying $10 per month for a full account, but the basics are enough to get started with. One feature I liked was that you can type in text on multiple lines, handy for doing narrow buttons with multiple words.