Just read Dennis' post about stripping language files out of iTunes. In general, how do you identify language files/folders in applications? Also, if the files are contained in a folder, is it safe to delete the entire folder -- or is it better just to delete the contents of the folder (leaving the folder itself)?

Really depends upon the application and much of the removal process is to play it safe and move them first instead of deleting anything, and then see if the app still works. If the app doesn't work anymore move the lang files back.

Example of making 7-Zip English only:
Delete everything except for "en.ttt" located in the lang folder.

There's some programs however that upon removing their lang files and when doing an online update will just download and reinstall them.

Just deleted all files in the 7-Zip language folder except "en.ttt" and that reduced the size of the folder from about 1MB to about 12KB.

Thanks to Dennis' post and this post, which served as a reminder, I will be checking all program files for useless unneeded language files. Before deleting I will first move them to make sure the program still functions properly.

I use the CCleaner winapp2.ini cleaner below, and never have to manually do it. Actually I typically make batch files to do that and place them with the programs setup file however since I use CCleaner everyday I won't forget to remove any lang files.