The first nightly build of popular custom ROM CyanogenMod 9 for the Samsung Galaxy S III is now available for download. Following the release of several unofficial builds since the S III's international launch in late May, the first official nightly is available at the CyanogenMod download site. CyanogenMod 9, which is based on the Android Open Source Project, offers an experience closer to stock Android 4.0, as opposed to Samsung's TouchWiz UX.
Initial feedback from early adopters has been positive, and the list of known issues point out only a couple of minor issues with FM radio and camera flash. But as with any unofficial custom ROM, you'll need a rooted phone with a custom recovery to flash this, and you'll void your warranty in the process, so proceed at your own risk. Check the source link below for download links and more information. We should also note that this ROM is for the international Galaxy S III only -- that's the one that's on sale in Europe and Asia right now, with the product code GT-i9300. The North American LTE version, due for release in the next few days, uses a different chipset and is not compatible.
If you've already bitten the bullet and installed CM9 on your Galaxy S III, be sure to let us know how you're getting on down in the comments!