MidiKit is a MIDI file utility program. It allows you to quickly modify the file type, creator, format and more, processing up to 400 files at a time. It has a complete online documentation you can access selecting the "About Midikit" item in the apple menu.
MidiKit 2.2 is FAT (68K e PPC native), and supports Drag & Drop. You may now modify copyright messages, even on a multiple selection. It works on all Macs from Macintosh Plus and requires MacOS version 6.07 or greater.
MidiKit is shareware ($12). Unregistered version have no other limitations than the annoying request at startup. If you use it, please register!