Just to make that clear: the MIDI file standard does support lyrics to some extent, just abc2midi refuses to conform. (This seems to be "not a bug, but a feature" for sake of an obscure karaoke software - who wants that? Can we hope for better-behaved software?)

For some of the real drawbacks of MIDI files mentioned by Artful (30 Apr 13 - 12:56 AM), MidiZyx2abc provides makeshifts, but whenever MusicXML is available, it should be preferred, using the Python tools abc2xml.py and xml2abc.py. These tools work surprisingly well in ordinary cases, including choral lyrics - I tried them myself.

Let me take the opportunity to thank all authors of truly free software, and to encourage them to improve it further. Commercial progammers of high professional quality are also welcome, and so are those who invent good standards. There is still a lot to do.