Drag things, pick colors, make a nice class for your buttons... introducing the Button Maker.
Boy, that's a nice button right there.
I'm saying "CSS3", because these make use of gradients, shadows, and rounded corners which contribute greatly to their button-ness. In older browers that don't support these properties, the fallback is solid-color background, no shadows, and square corners. Not a big deal.
I hope this is painfully obvious, but to use this Button Maker thing, you just adjust the settings until you have a nice looking button, then press the button and it will give you the CSS. Copy and paste at your leisure. Now you can use the class name "button" on HTML elements to make them look like buttons. The CSS isn't formatted real pretty. If someone has an idea on how to make that better, please do let me know.
The super-awesome empowering concept...
...in regards to how the Button Maker preview works.
OK OK I'll get on with it. The idea is to append a <style> element into the <head> which overrides the existing CSS (in-document CSS automatically overrides linked CSS for selectors with the same specificity value). Then when something changes, you literally rip the whole style tag out, and replace it.
Appending a new style:
Text variable where the CSS will be kept. Keep this text up to date when options change.
var cssText = "";
Use the replaceWith() function to rip out existing style element and apply a new one:
$("style").replaceWith("<style type='text/css'>" + cssText + "</style>");
The ripping-out part is important. Originally I tried putting an ID on the style element and replacing the content within it on the fly. It did replace the content, but those changes were not reflected on the page. Apparently in order to force the browser to re-render with the new CSS, you have to literally remove it and put it back.
Take it, shake it
I'll provide the source for the thing in case you want to run it locally for whatever reason. Or even better, because you want to make it cooler. If you do, please share.