Buttonator.com provides an online service to create nice and beautiful buttons without using Photoshop or GIMP. All you need is a browser (Web 2.0 compliant) and internet connection.
You can select the available button styles, and modify its color, text fonts, width, height, text colors, strokes, and lot more.

In fact its a great online service for those who doesn't have Photoshop or GIMP. This doesn't require any expertise in graphic design. Any newbie can accomplish the button creation.
Checkout this service and create your customized buttons for your blogs and websites.
You can also avail the premium service, apart from the free service available.