What do you mean by alternative? Adobe Flash Player works just great on the S3. It's recently been removed from the Play store, but apps like
this one will allow you to download it directly from Adobe. You can also search online and download the APK and install it that way.
HTML5 is what is slowly replacing Adobe Flash online, but it's going to take awhile before everyone is using it. And it's implementation is on the website's end, not the user, so people will have to wait until the website makes the switch unless you're able to convert it...
...and a browser like
Skyfire is a way to get to most Flash content via conversion. What Skyfire does is render and convert sites on their servers and then it gets sent to your device (with most browsers, everything is rendered on the device). For Flash content, Skyfire converts it to the aforementioned HTML5.