A few years ago (2008-2009) I started to develop a Windows application to ease the tedium of adding OpenType features to fonts. I had to set it aside then, but I am now working out the kinks and finishing it off. And I wonder if it would be of any interest to fellow typophiles?
It opens an AFM file to get information about the glyphs in a font and then autogenerates classes and features based on glyph naming (and suffixes in particular). It also allows manual creation of features and exports a feature (FEA) file.
If there's interest, I'll package it up and share it. Again, it's a Windows application and requires the .NET Framework.
Download and give it a try: http://www.timrolands.com/More/Downloads.aspx