Great idea to seek some feedback from customers on this!
ESV B-Ionic
Higher quality T5 fixtures - either ATI Powermodule or Sfiligoi Mini Stealth (someone in Canada has to start regularly stocking a 24" 6 bulb T5 fixture eventually - you'd likely see a lot more customers starting up smaller, but high end tanks in smaller condos downtown if they could find something adequate and, um, not ugly like the Tek lights)
Premium Maxi-Jets (we've already spoken about this
)
Now that you're selling some fancy colored polyethylene tubing you might as well sell some quick connect/compression fittings such as John Guest fittings