Allthough not earthshaking there is a nice article on the devshed about formatting HTML forms. Click here
The highlights for me are the tabindex, the accesskey and the fieldset. In one of our projects we built an HTML application with a lot of data entry. The users quite rightly were a little bit worried about having to navigate with the mouse for everything they had to do. Introducing the accesskeys and the tabindex completely removed the mouse from the picture. A simple, effective but often forgotten way to achieve user friendliness of your application.
The fieldset was completly new for me. An elegant way to enhance appearance of your form.