Ok, this is what people could/should do...
1) Not continue to make more of the Vick incident than it is. He tortured/killed dogs and financed a dog fighting ring. He got what he deserved legally and financially and in the eyes of the public his image is irreparably damaged. To pile on at this point is either insincere or obsessive. If we still value rehabilitation as we say we do, let the man get on with his life. Protesting at this point would be counterproductive. What more could we get out of keeping Vick out of football than we could by letting him play?
2) Reserve their venom for people and acts that deserve it. No one is saying people shouldn't be upset with Vick, but when that is seen with more disgust than a homicide and theft of a fetus, something is wrong with our society. The more attention we give to Vick, the less goes to items that deserve it. The media reports on what we signal to them we want to see, and if they're talking about Vick we must want more Vick. Thus, when we complain that the media is obsessed with a story like his, they roll their eyes and toss on another Vick segment.
3) Not get so caught up in the idea of celebrity. This is the main factor warping our idea of criminality and justice. If Michael Vick were some no-name kid who worked at a gas station and did what he did, no one would have given a rat's ass about the act after the first 24 hours. We have it in for famous/rich folks. Dog fighting/killing/torture has been going on for centuries. We continue to do little about it and public sentiment is fairly non-existent.
As for the outrage, I could be overstating it, but in comparison to the outrage I see for Vick versus that for other criminals, it doesn't seem too close. Some people just like to latch onto a story or person and ride their "outrage" to death. Maybe it makes them feel morally superior. In fact, if most of these people thought about it, they probably would admit that they're not that outraged about the whole situation anymore. PETA always tends to latch onto a case like this for publicity as much as anything else. When the Vick publicity train started to peter out, PETA moved on.