Great add-on, FF should have an interface for setting preferred ways to open files based on their extension. I wanted to open .java with FF as text/plain. But after playing around with mimtypes.rdf, I couldn't succeed - I still got the DL window with "Open with" and "save" and it still displayed the .java file as "JAVA file".
Open in Browser lets me open it in FF as txt, but there should be 2 more features:
1. open in new tab - if I click the .java link in a new tab, it doesn't open the file. Also, even if it did, there's a problem for JS links, which you can't open in new tab.
2. I can't tell the add-on to always open files with a certain extension the way I want.
Overall quite useful and time saving.