I haven't seen this anywhere other than on the O'Reilly Radar so I'll give it some more visibility (thanks to my awesome Google PageRank): Platypus.
Creating scripts for Greasemonkey was pretty simple, but now it's ridiculous. When this gets out there's going to be an explosion in the number of scripts. I activate the extension, click around one the screen a little, and suddenly I have a customized page (within reason). In some ways, the whole web just became a portal.
Now we just need an easier/integrated way to share these scripts with the world. I wonder if you can write a greasemonkey script that modifies another greasemonkey script to insert a link. Ideally, the link would submit the title, description, and target pages of the script (pulled from the standard comments) along with the script itself to the repository of scripts.
Oh! And then... (this is like the 3rd edit of this post), we need an easier way to discover greasemonkey scripts that people have published. I need something to alert me when there's a greasemonkey script available for the current page I'm on--similar to the RSS auto-discovery feature.
And then... we'll do it all over again for Trixie.