While MIDI files can't compare to the MP3 for sound quality, they have tons of uses and can be tons of fun, too. MidiGlassPlayer is a free player that doesn't look like much but handles any type of MIDI files.
We never judge a book by its cover or a program by its skin, but not much about MidiGlassPlayer's user interface, from the purple fade to the scattered player buttons, appeals to our visual senses. Dragging resizes the window but not the control area (it stays the same size) and shading makes the toolbar difficult to see. MidiGlassPlayer does have the old-school look of a personal project that has evolved over time. But, a program's beauty is only skin deep. What matters is how it performs. And MidiGlassPlayer does its job quite well. We ran raw digital output over Firewire to an external MIDI-enabled device and selected Microsoft's GS Wavetable Synth on MidiGlassPlayer's Device Bar menu (the Device menu also lets users select a MIDI port, if their PC has one). We downloaded a free MIDI and opened it in MidiGlassPlayer (we use ZZ Top for listening and The Village People for awful puns). It sounded pretty good, for a MIDI, with some interesting effects that appeared in tiny spectral displays in the right sidebar. MidiGlassPlayer's speed slider changed the tune's tempo without altering the pitch, with interesting results.
MidiGlassPlayer isn't the prettiest face in freeware, but as a MIDI player, it's well worth a look.