CyanogenMod 10, the popular custom Android ROM that replaces a phone's default software, has been released in finalized, stable form today. Available for a number of devices both new and old, the latest version is based off of Android 4.1 Jelly Bean. A large part of CyanogenMod's appeal is that it closely adheres to the stock, untouched Android experience increasingly found only on Google's Nexus devices: there are no traces of overwrought "skins" here. Owners of the Galaxy S III, for example, can finally opt to ditch TouchWiz in favor of a stable alternative. It could also prove a popular path for anyone disappointed by the Nexus 4's lack of LTE: you'll be able to get a largely similar experience on a 4G handset with this ROM.
Further, CyanogenMod can breath new life into a phone no longer receiving software updates or other official support from a manufacturer. Downloads of the ROM are available today for a number of devices that have long languished on legacy versions of Android. The Samsung Captivate and Galaxy S II Skyrocket are just two examples, though even CyanogenMod's developers have their limits when it comes to hardware support.
Naturally you'll want some working knowledge of Android before diving into the process. The installation procedure has become almost foolproof these days, but you should nonetheless take care to avoid being left with an overpriced paperweight. The full list of stable CM10 downloads for supported devices can be found at the source below.