Go sign up for Flickr and a Yahoo account. Play with it for a while.
They have really, really good forms. Friendly, simple, and clear as a bell about what you should do next.
For me, I think this sort of bare-bones usability improvement is the best thing about the whole Web 2.0 movement.
If you want to do one thing to your web site that will increase conversion rates, close more sales, reduce customer service costs, and make a lot of people happy — fix all the forms.
More:
- Look here for someone who is a really good at it on the 37Signals Gig Board
- Best Practices for Form Design presentation by Luke Wroblewski