<div id="filters">

  <ul>

    <%= form_tag "", :method => :get do %>

      <% filters.each do |filter| %>

        <li>
          <select name="<%= filter[:filter] %>">
            <option value=""><%= filter[:message] %></option>
            <% filter[:items].each do |key, value| %>
            <% selected = "selected" if params[filter[:filter]].eql?(key.to_s) %>
            <option <%= selected %> value="<%= key %>"><%= value %></option>
            <% end %>
          </select>
        </li>

      <% end %>

    <li>
      <%= submit_tag _("Filter"), :name => nil %>
    </li>

    <% end %>

  </ul>

</div>

<div id="filters">

  <ul>

    <%= form_tag "", :method => :get do %>

      <% filters.each do |filter| %>

        <li>
          <select name="<%= filter[:filter] %>">
            <option value=""><%= filter[:message] %></option>
            <% filter[:items].each do |key, value| %>
            <% selected = "selected" if params[filter[:filter]].eql?(key.to_s) %>
            <option <%= selected %> value="<%= key %>"><%= value %></option>
            <% end %>
          </select>
        </li>

      <% end %>

    <%= hidden_field_tag :search, params[:search] %>

    <li>
      <%= submit_tag _("Filter"), :name => nil %>
    </li>

    <% end %>

  </ul>

</div>

Include params[:search] as a hidden field
Include params[:search] as a hidden field
