While I was browsing Smashing Magazine's website, I discovered this cool article with a download to some awesome CSS buttons.
The great thing about these buttons is that they are pure css! No images at all! Even the icons, and sprites are coded.
This was achieved with the clever use of a vector font face, pseudo-elements, and css styles. The buttons are fully customizable, and scalable to whatever size you may need. All image free.
These buttons are available for free at the developer's website.