CSS3 is awesome, but the new syntax is sometimes hard to get your head around. Thankfully though, a few kind souls have created some very useful tools to generate the code for you.

CSS3, Please! The Cross-Browser CSS3 Rule Generator

http://css3please.com/
Developed by Paul Irish and Jonathan Neal, this tool is incredibly easy to use.

CSS Border Radius

http://border-radius.com/
Developed by Jacob Bijani, the Creative Director for Tumblr.

@font-face Generator by Font Squirrel

http://www.fontsquirrel.com/fontface/generator
A very hand tool for creating proper @font-face code. Font Squirrel also provide a huge library of free-to-use fonts with @font-face code included.

CSS3 Generator

http://css3generator.com/
Developed by Randy Jensen this tool has a bunch of different generators for creating CSS3 code. This tool can create multi-column code

Western Civilisation’s Text Stroke, Text Shadows, Box Shadows, Transforms & Gradients Generators

http://westciv.com/
Western Civilisation creators of the CSS code editor, Style Master have created no less than 4 tools for generating CSS3 code.

The Text Stroke tool

http://westciv.com/tools/textStroke/index.html

The Text Shadow tool

http://westciv.com/tools/shadows/index.html

The Transforms tool

http://westciv.com/tools/transforms/index.html

The Linear Gradients tool

http://westciv.com/tools/gradients/index.html

The Radial Gradients tool

http://westciv.com/tools/radialgradients/index.html

The Box Shadow tool

http://westciv.com/tools/boxshadows/index.html

CSS3 Gradient Generator

http://gradients.glrzad.com/
Developed by Damian Galarza this tool also creates the code required for CSS3 gradients.

Please let me know if I have missed any, and also what you think of the list.