It would be nice to have some hooks exposed to add support for other formats through externals converters.
For example, I've written a VSD to SVG converter and it would be nice if I could integrat it with yED and add support for VSD to yED with something like a little xml:
<external_open>
<format>.vsd</format>
<command>vsd2svg</command>
<args>
<arg>-i</arg>
<arg>$INPUT_FILE</arg>
</args>
</external_open>
This example is of course too simple, but it gives the general idea.
For reference inkscape does that with its script extensions
