Fair warning: this is a VERY rough port.
*You can put in your server address and api key in the settings.
*NZBMatrix is the only supported site (I'm too tired to work out the others at the moment)
*No popup dialog
*You will not see a little green icon after you hit the add button
I will add the other indexing services in tomorrow if I get a chance. I'm working on getting some of the other feature in too, but I really need to focus on my iPad app
Anyways, I have linked to the extension below. I'll post updates here as I have time. I'll also post the source after the next version (it looks pretty gross right now).