Update: This should be read rather as: "Convert files via small drag&drop application"
This is a follow-up of
http://brainstorm.ubuntu.com/idea/12551/
How about developing a file conversion-plugin for Nautilus file manager?
You could select one or multiple files, right-click and select a context-menu entry like "Convert files to ..." which expands to state all the possible file types of conversion. This would then show a dialog of options (if applicable) and let you convert your files directly from the file manager.
New files should get their extension adjusted. A switch should allow keeping or abandoning original files.
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Example:
Select 4 mp3s, options could be "ogg", "mp3" (to alter compression), "wma", "wav" and maybe "flac". Selecting one would show a simple compression slider (for ogg and wma).
You select multiple documents of odt, ods and odg type (your custom project), right-click would show only "pdf". If you clicked odt only it would show "doc" as well.
Of course, the real file type should be shown, not only its extension.
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I don't know how hard it is to implement the de- and encoding of the relevant file types, though. There should be some standard libraries for quite a few, probably.
Also, this is somehow in the spirit of conduit's (
http://www.conduit-project.org/) data streams, wildly converting data types while producing backups.
