RestResponses is a couple of useful little methods to clear up your restfull controllers, turning something like this:

  def update
    @user = User.find(params[:id])
    @user.update_attributes!(params[:user])
    respond_to do |wants|
      wants.html { }
      wants.xml  { render :xml => @user.to_xml(:except => :hashed_password) }
    end
  rescue ActiveRecord::RecordNotFound
    render :nothing => true, :status => 404
  rescue ActiveRecord::InvalidRecord
    respond_to do |wants|
      wants.html { }
      wants.xml  { render :xml => @user.errors.to_xml }
     end
  end

To this:

  before_filter :find_user

  def update
   @user.update_attributes!(params[:user])
    responds @user
  end

To install: ruby script/plugin install http://rest-responses.googlecode.com/svn/trunk/rest_responses