Ruger's latest 22/45 offering:

[Grenadier]

...the 22/45 Lite:

http://www.ruger.com/products/2245Lite/models.html

This one comes in about 8-10 ounces lighter than the standard 22/45 or Mark III, thanks to an aluminum upper. It also seems to have a lot of nice features from the factory as well. Folks who shoot the steel challenge matches might find this one to be a great gun.

Now, if it only weren't gold-colored...