Shameless plug, I have a webservice (http://thumbr.it/) similar to your project, but I also added instagram like filters to the images and it converts word and pdf files to images, and I'm adding html and pdf as output formats and html as input format.

It's a pity that docverter didn't work (so far?). Have you tried broadening a bit the range of formats that you cover? Obviously (as I'm also working on the same space) I think there is a real need to cover here. Good luck!