by ergonis software PopChar is a utility application that lets you insert special characters, accented letters, umlauts, etc. into any document. No need to search for or remember complex keystrokes. Unicode fonts are neatly arranged in the standard Unicode categories.
by Cool Engineering renames files and folders for a next-coming FTP-upload that way, that it replaces invalid characters with an underscore "_". German special character as ä, ö, ü, ß will be replaced with "ae", "oe", "ue" and "ss". The filename will be lowercased.