The Sun ODF Plug in 1.0 for Microsoft Office gives users of Microsoft Word, Excel and Powerpoint the ability to read, edit and save to the ISO-standard Open Document Format (ODF = Open Document Format). I originally planned to list it as Open Source here. But, it looks like it is closed source. Its download page does not link to its source code just a binary EXE file. I find this kind of ironic (closed source for an open format).