There are lots of double-gate MOSFETs commercially available. They are often used as mixers, but can also be used in logic and amplifier circuits, amongst others. Wikipedia has an example showing a common device:

http://en.wikipedia.org/wiki/Multigate_device

There is a Springer book on the subject which you may find interesting:

http://link.springer.com/chapter/10.1007%2F978-0-387-71752-4_7

If you are using spice simulation then there are models available for double gate MOSFET from PTM (Predictive Technology Models) for 32 nm and 45 nm technology

http://ptm.asu.edu/modelcard/45nm_finfet.rar

http://ptm.asu.edu/modelcard/32nm_finfet.rar

You can use these to simulate your circuits.

Use H SPICE and PTM models. That would work.