My next 22 pistol will be the Ruger 22/45 Light with a Class 3 Supressor. Buddy has one that's a blast for squirrel hunting in the backyard.
Like Mark mentioned, a 1911 in .22lr is a blast also. I've got a Kimber Match Target 1911 Custom Shop in .22lr that will shoot 1/2" 10 shot groups at 25 yards.
Mark didn't mention a .22LR in a 1911.
A .22LR in a 1911 is just crazy good and great for training.
Personally can't stand the 22/45, but they are a great pistol (the ergos for me are FUBAR). The MkII, though... yeah.
A suppressed .22LR is on the very short list.