If you use IE and you use the Google toolbar you might of noticed that your input boxes have a nasty yellow background, this is due to a new feature in the toolbar to help "autocomplete" the fields.
Now if you've just spent hours on your CSS and design this can totally ruin the look/experience that your customers should have when visiting the site. Over at http://jenseng.com/ there's a good bit of info about outsmarting the Google Toolbar which includes a Js work-around that prevents *style hijacking*. Well worth a look at if you want to keep the style of your forms.