Have you ever been annoyed when you wanted to see a document and the download popup appears which forces you to select an external editor to view it?
This extension allows you to open the document directly in browser. You can also change the mime type of a document being viewed (could be used as a source viewer).
This extension won't be useful anymore once Bug 57342 and Bug 258012 have been implemented.
Secondly, please could you fix the tab order on the Save As dialog? Apparently, with your extension installed, when "Open in browser as" has focus and I press Tab, focus goes to the "open with" drop-down, not the one I would expect. Similarly, if "Save as" has focus, Tab should go to the checkbox underneath, not the "open with" drop-down :)