This is a great thread, and has given me lots of valuable tips. Thanks to all.
In return here is one I just stumbled across:
http://media-convert.com/ This site allows you to upload an amazing variety of different file types from different applications, and it converts it to a file type you require. It converts documents, audio, picture and movies (although there is a limit on file size) and spits it back as a either a download file, zip file or just a link.
I know it's not really "Free Software" as such, but could be a bit useful (and still free to use) for any of us wanting to use our free files in paid applications or vice versa. Took about 30 seconds to convert an old Star Office .sxw file to a Microsoft Word .doc so I could e-mail it to someone else.
