Document conversion software
Have a file in one format? Wish it was in another? Don't want to own four different software versions that do the same thing, just to open the file? Fear not. Document conversion is possible by a number of different methods.
Built in Features
Check your save as feature when using the software you own. There is a good chance that it handles multiple file formats. Simply find out the extension (the three letters after the dot) that is used by the software your friends want to see the image or file in. If its on the list, you are in luck. Just use the save as button with that number highlighted.
Proprietary formats
Some software has a unique format and they charge for the right to use it. This is where document convert techniques come ito play. Specialized software is designed that recognizes hundreds of different formats and changes the file seamlessly. It is much better to have a single multi purpouse tool than individual software for each document types.
document conversion services
The internet has document conversion services. For a fee you can submit a document and experts will send it back to you in the desired format. They typically have a wide array of tools and are capable of batch processing.
Prices of document conversion vary considerably. One option which is free, but very useful for office type applications is open office software at http://www.openoffice.org. While this does not batch convert it handles a large number of filetypes.