I stumbled upon a new website today, iconizer.net, and it's just what a lot of customisers have been looking for: a way to quickly choose and customise icons for downloading, with a huge library of source icons, from several different OSes and styles. Available styles include MacOSX, Vista, Aero and others.
Here's a quick guide to creating your own customised icons with iconizer.net:
Once you've selected your category and style, click on the "Select Icon" drop-down box:
Finally, press "Generate Icon".
Et voila! You've got a lovely custom icon that you can use to populate a launcher/dock, or replace an entire icon theme (if you've got the time)!
Have you used iconizer to generate a custom icon? Want to share it? Post it here!