I was looking for a way to alternate table row colors with Ruby on Rails and stumbled across this gem. All you have to do is use the cycle method on the TextHelper.

 
  < %- for item in @items do -%>
    <tr class="<%= cycle("even", "odd") %>">
      ... use item ...
    </tr>
  < %- end -%>
 

and in the css:

 
.even
{
    background: #efefef;
}
 
.odd
{
    background: #a5a5a5;
}
 

The love affair with Ruby on Rails continues… :)