To convert images, the graphviz package contains a utility called convert.

Example:

convert -scale 300x150 -transparent white klingel.svg klingel.png

Office files

You can convert Office files (*.doc, *.ppt etc) using the command soffice:

soffice --convert-to png presentation.odp

Converts presentation.odp to presentation.png

Corel Draw files

To convert a Corel Draw file to a Linux-readable format, use uniconvertor.