One extremely interesting idea to increase your revenue (and us) is to provide customisable spread products
i.e. I can trade IWM / SPX or Barclays / RBS or 0.8 * Bund - TY
Obviously you can charge bigger spreads for these products (not too large so customers can still potentially make money)
While the charts, alerts, limit and stop loss orders you can provide for these customisable products would be extremely interesting and valuable