Today, the Mark II and Mark III, and the .22/45 versions, which are later versions of the original Mark I are still the staple gun of Ruger. They are known to be very reliable for rimfires, which are usually notoriously unreliable.
Ruger also has a very popular and well made semi-automatic carbine, the 10/22, as well as a wide array of revolvers and semi-automatic pistols geared towards law enforcement and self defense. They also make some shotguns and other rifles.
Ruger Mk. II and .22/45(.22lr) ~$450
Ruger 10/22 (.22lr) ~ $150
Ruger Single Six (.22lr)
Ruger Redhawk Alaskan (.454 Cassul)
Ruger PC9 (9mm Carbine)
Ruger P89 (9mm)
Ruger P345 (.45ACP)
Ruger GP100 (.357 Magnum)
Ruger SP101 (.357 Magnum)