Create custom icons for websites iPhone

Are there any good tools out there to create custom icons for the iPhone for website bookmarks? Some websites have them already, and Id like to make my own instead. And some dont have one at all, so all I can do is create a webclip of the site, which looks terrible. I used to use Clipalizer.com but they went under. That was basically a redirect that they hosted, where I could use my own icon. And now I have found another bookmarklet that works for some sites, but not all, particularly Google Docs site, which is its own inherent icon. Any ideas?
MacBook Pro, iMac, iPhone Mac OS X (10.5.2)