
  For instance, I can be helpful in one community and have a ton of reputation but a complete 'weirdo' in another.


You are making points against yourself in your argument for the feature. That reason, right there, is exactly why this is a bad idea. Just because you are skilled and knowledgeable in one field and community doesn't mean you know what you're doing in another.

While the system and features of each site are the same, each community is different. They develop their own quality standards and their own expectations, and it doesn't make sense for reputation to carry over across all sites.

The system already gives you a small reputation boost up to at least 101, so long as you have at least 200 reputation on any other site in the network. That lets you get the two most basic features: upvoting and commenting. Privileges past that become highly dependent on the community in which you're participating, and it's dangerous to let just anyone out of the blue show up in a community and start editing or voting to close things when they've never participated there before.

Consider Global Reputation Points
In Settlers of Catan, I sometimes try to ask people if they want to trade a certain resource, tricking them into revealing the approximate amount of that resource in everyone's hand. After this I play the monopoly card. This has on some occasions not been received very well.

Is this fair play?
