I built a Greasemonkey userscript for Firefox and Chrome, and I now want to convert it to a Safari extension and an Opera extension.
Are there any compilers out there like Arantius' Greasemonkey-to-extension compiler but for Opera or Safari?
There isn't a good compiler for converting userscripts into Safari or Opera extensions. Some userscripts work on Opera though, and there are some older Safari extensions that run some userscripts, but I don't hear good things about them.