I just bought a couple of the Vortex Crossfire 1X muzzleloader scopes and mounted them on 22s. I bought the from the Camera Land Deal of the Day list for $80 each. They are terrific on a 22. I like low magnification scopes on a 22 and this is perfect for my Marlin 39A.

I don't believe they are "really good" scopes, but I bought two Barska 2.5x fixed power scopes to put on my kids' .22 rifles. It's a light weight, low power scope for them to start with, and not too expensive to replace if they get dinged up.

Leupold makes an excellent .22 scope, the "VX-2 3-9x33mm Rimfire EFR". But it wouldn't be the best option for a light rifle, like the Marlin 39A, or for a cheap kid's rifle.