" we could write an algorithm that gives stuff and people get expert cred when they are upvoted by the established experts"

Sounds like StackOverflow (http://stackoverflow.com)

It is a domain-specific community (everything about software development), in the form of questions and answers. Reputation is earned by upvotes from other community members. Naturally, the established experts emerge as high-reputation members, being those with a long history of giving good answers.