Software is one of the fastest growing areas of MIDI.
What DAW software (Cubase, Logic, Performer, Pro Tools, Sonar, etc.) do you use?
How about mobile apps for iPhone, iPad, or Android ? What about web sites that let you do notation, music production and synthesis in the cloud using Web MIDI.
There are tons of MIDI utilities for helping you do all sorts of different things with MIDI.
Here is where you find articles on anything that is MIDI software.