Hi recently we developed a Silverlight component for one of our client and used some very interesting technologies. I thought those are worth sharing. If you are thinking about converting your PDF document to word or some other format I would suggest you use BCL component. You can download the sdk as well as the trial software from http://www.pdfonline.com/.
There could be lots of technologies for converting documents from one format to another but sad thing is noting is free. You have to pay to use this component so some financial bottleneck is involved. I would very much like to see some free component in future. In those cases open source software's would have had those rich conversion facilities.
Until we find free products for conversion, this is a good choice.