Rails doesn't have reset_tag to automatically make a form reset button, instead you have to take a slightly different route. To make a form reset button in Rails you simply do this:
[source:ruby]
< %= submit_tag("Start Over", { :name => 'reset', :id => 'reset_button', :type => "reset" }) %>
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which will create the following:
[source:html]

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The important part here is the :type argument, which override's Rails' default of "submit" for the submit_tag. Then, to tidy it up a little I override the :name, which defaults to "commit", and give it a useful id attribute.

Et voila!