Installed them today (XS Ghost ring sights for 10/22) :
XS Ghost-Ring Hunting Sight Set Ruger 10/22 Steel Matte
Those are new grips on my MKIII too I really like them (hogue ambidextrous from shopruger.com).
The stock Ruger front sight was a PITA to remove... but once it was out it was easy to install the XS front sight. I just laid the barrel tip over a roll of electricians tape and knocked it out with a brass punch and hammer. I haven't taken the rifle to the range yet but my impression is that I like the sights and can't wait to see how they shoot at 50 and 100 yards. The rear aperture is bigger than I expected... It came with two and I install the smaller one.
I think I'll take a better camera with me to the range and update this post with new pics and shooting impressions.