Adding Custom Fields to WordPress Comment Forms?

What is the best way to add custom fields to a WordPress comment form?
(for example subject, image, etc…)

And how do I use the data entered afterwards…

Hi @hannit cohen:

This slideshow from Beau Lebens should be able to show you how:

• Hooking into Comments

And this blog post from Otto should be able to show you more:

• WordPress 3.0 Theme Tip: The Comment Form