>>If the laptop also has DisplayPort you might be able to daisy-chain DisplayPort monitors e.g. http://www.displayport.org/cables/driving-multiple-displays-from-a-single-displayport-output/
>
>This one does not have a DisplayPort. This page details its content:
>
>http://www.01net.com/fiche-produit/fiche-technique-14649/pc-portables-sony-vaio-duo-13
>
>>I believe Thunderbolt can do that too but I don't know if it's made it into real-world PCs and monitors yet.
>
>Thanks, I will take a look at that.

From the spec sheet it doesn't look like the machine has Thunderbolt.

It looks like you can use USB:

1. Plug a powered USB3 hub (you don't want an unpowered hub) into one of your USB3 ports e.g. http://www.amazon.ca/Plugable-USB3-HUB7-81X-Seven-Port-Four-Amp-Adapter/dp/B008ZGKWQI/ref=pd_bxgy_ce_text_y

2. Buy two of these to create 2 HDMI or DVI outputs for 2 external monitors: http://www.amazon.ca/Plugable-Multiple-2048x1152-1920x1200-DisplayLink/dp/B007L6NYAO

3. Plug the 3rd external monitor into your HDMI port

With that setup you will still have 5 free USB3 ports on the powered hub so you'll actually gain, rather than lose, ports.

I haven't tried this, if you go this route I'd be interested to hear your experiences.