Finale NotePad is a simple notation software that allows you to create fully notated music scores. It does not have the flexibility and power of its big sister Finale, but it is free. This software will also allow you to see, play, and print any music scores created in Finale by others. This will be especially helpful to choir students who wish to view the music while they hear it being played.
This is an excellent demo program, but does not allow you to print or save. However, you can view and play any Sibelius file with the demo, and play midi files as well. The features that make this demo program worth having are its playback capabilities. Tempo is easily adjustable. It has a mixer, so that individual parts can be boosted, and other parts can be softened. Since Sibelius is notation software, it also shows notes on the screen.
MuseScore is a free, open source full featured music notation program. With this software you can control tempo and boost your own individual part using their mixer interface. MuseScore is available for Windows, Mac and Linux operating systems. You can download the MIDI files from this site onto your hard drive and then open them with MuseScore.
Notion is for the iPad. I have not tried it. You can create notation files within it. It imports Musicxml files as well as midi, which is a huge plus. $14.99.
Not a notation product specifically, but its pdf markup ability and ability to import audio files makes it very useful. Mac, iPad and iPhone platforms.
Free notation software for the iPad.