I'm sure it would be quite easy to program a visual basic program to do this (I'll add to my list)

There is another way which I have seen and used.

Powerpoint, which is the presentation part of the Microsoft office group of products allows custom Animations.

I have been in a few of these weird company focus workshops where they sing a company song.

I help them set it up,

Firstly we typed each line or verse in as a text object. Spread it over a number of pages to make it readable on a laptop at about 24-30 point text.

Then assign each verse or line as a custom animation.
Then use the auto timing feature.
This allows you to generate your own timings for when the text scrolls in, or appears and when it scrolls out.

The best way is to play the song at your tempo, and ask someone else to click the mouse following the lyrics.

It took us about 10 mintues to generate a stand alone presentation for a 3 Verse - Chrorus song.

And it worked !!!!!!!

The file was less than 50K as I remember.

The Alternative would be to use a USB foot switch, to scroll the next verse/line of text as required.

Which is a better soloution if you often change tempo or repeat sections.

I know this sounds complicated, but it really is very very simple, the help files in Powerpoint show you how the custom animation feature works.

We used a projector so all the office morons could sing along, but it will work for a single user on a lap-top in the same way.