Convert many file types using Zamzar.com's free server and API. Easy to use program. C# source.
A Windows Executable is also included if you don't wish to recompile.
Can convert image, audio, video, document, and other file types from one format to another. For instance, a .pdf document can be converted to a set of .jpg images, one image per page. Or convert a .wav file into a .mp3 file.
You do need a free ApiKey from Zamzar.com (https://developers.zamzar.com)
There is a file size limitation with this ApiKey, and also a limit on number of conversions in a month, currently 100. That should be more than enough for most people.
More information is in the READ_ME.txt file.