If you would like to save FlashForward or at least give it a try, head over to Save FlashForward Center, where you'll find everything you can do, if not to save the show, at least to make some noise so ABC gets to know that people did watch the show and did care about it.
Save FlashForward Center is not just about a petition online or a web campaign that doesn't do any effect on the real world; on the contrary, it's got everything pretty well laid out and constantly updated to let you know what to do starting by phone calls and letters and from there to well organized campaigns on Facebook and Twitter.
If you liked the show, you should check out that site. As I said above, even if the show doesn't come back, fans shouldn't let it go without making their voices heard.
Disclaimer: I am not affiliated in any way with Save FlashForward Center, but I support their cause. Why? Read here my previous post on the subject.