autocomplete="off"
this should fix the issue for all modern browsers.
<form name="form1" id="form1" method="post" autocomplete="off"
action="http://www.example.com/form.cgi">
[...]
</form>
In current versions of Gecko browsers, the autocomplete attribute works perfectly. For earlier versions, going back to Netscape 6.2, it worked with the exception for forms with "Address" and "Name"
Update
In some cases, the browser will keep suggesting autocompletion values even if the autocomplete attribute is set to off. This unexpected behavior can be quite puzzling for developers. The trick to really forcing the no-autocompletion is to assign a random string to the attribute, for example:
autocomplete="nope"
Since this random value is not a valid one
, the browser will give up.