Check out this tutorial on how to configure the firefox ViewSource extension. It focuses on using Vim as the external editor, but you can easily use other programs, so for example I’ve used these instructions to make it possible to right click inside any form element (including my weblog) and pass the contents to Textmate, where I can use a real full-featured text editor to work with instead of the bare bones traditional HTML form area. The same principle applies to images – configure it appropriately and you can right click on any image you’re looking at in your browser and pass it to your favorite image editor. It doesn’t sound like much, I know, but it’s actually really handy. The only downside is there’s no way to pass things back to the browser so you’re still stuck copying and pasting, but even so this is a time saver for me and made it much more likely that I’ll do things like spellcheck my weblog postings.