This type of punishment system doesn't really seem like it would help build a team dynamic - quite the contrary. I believe it was The 7 Habits book from Covey wherein he describes a sales force who was offered a reward to the individual with the most sales. This led to backstabbing, stealing each other's clients, etc. - because the individuals, who were supposed to be a team, were competing against each other. In this scenario you are competing against yourself - but with a potentially geometric increase of pressure - which, eventually, will lead to a feeling of insurmountable odds and giving up. Your goal is 300 - you don't make it - now you have to do 700...what happens if you only get 300? 2*400+100 - now you have to get 900?
Try to find ways to make the goal for the whole team - 900 link backs - and the punishment non-geometric in increase and, again, for the whole team. By doing this those who are simply better at the task will make up for the less-skilled members of the team in that area of measurement. Going back to that line I've seen recently attributed to Einstein - Everybody is a genius. But, if you judge a fish by its ability to climb a tree...
Also, try to establish a team goal relevant to an individual strength each member possesses. For example, maybe you're really good at creating content that gets back links. Maybe someone else in the team is really good at writing code. Maybe the last person is really good at networking. Set 3 goals: (1) 300 back links; (2) 50% reduction in the number of defects released into the wild (character encoding issues, I don't know your situation well enough to give concrete examples); (3) increase traffic from networking sites by 10%.
Make the punishments for the whole team - all for one and one for all - but don't make it an increase on the goal itself...that just leads to problems. (You couldn't get 10; so, now you have to get 20 - you couldn't get 20; so, now you have to get 30 - eventually someone is going to ask the question: Or, what? What will happen to me if I don't make it...the world hasn't ended from me not making it before. Will I get fired - might not be such a bad thing with these expectations. This happened to me recently in fact, it led to me doing 15 hour days for about a month until I finally said, "I'm done..." - the world didn't end, the client didn't fire my company, I didn't get fired from my company, and - funny enough - people stopped pressuring me.) And, just to suggest something completely out there - try a reward system instead.
If you all get more motivation from not wanting to get hit with a stick, okay. But, what's the carrot here? And, to Gruber's point regarding "if you really need the threat" - I would say, if you need to threaten or punish people to get them motivated - they probably shouldn't be there in the first place.