Tell PG/HN: I want a tooltip summary

A lot of the time I will go to hacker news and quickly scan article titles for something interesting. While I know the mods try to change titles to be more descriptive, some things are just ambiguous. Right now there is an article called "A Rare Disagreement" on the front page. Now that could be about anything, and I don't know if I really want to spend my time on it. Can we add a little box on the submit form for an excerpt/summary that would appear on hover? Or maybe a little down arrow that you could click to expand the summary? Limit it to 150-300 characters and it could be a great improvement to the front page.