My Cool Button is an excellent online tool for creating Web 2.0 style aqua buttons with rounded corners and color gradients. It generates the final image in PNG format.
This button generator is so simple and intuitive that even a three year old can produce professional looking Web 2.0 buttons in seconds. Do add it to your Web 2.0 designer toolchest.
Related: Web 2.0 Logo Tutorials | Online Logo Generator