creating a decentralized web of trust

I've been working lately on creating an identity provider based on the
github API

In weaving the web, timbl wrote: "The trust engine is the most powerful
sort of agent on the Semantic Web" and Im trying to look for ideas on how
to create such a thing.  Note also that this group incorporated the web of
trust group some time back.  I think when reading and writing to the web
it's going to be increasingly important to know whether or not you can
trust someone with write access.

So, Github provides a number of social signals:

- followers
- date joined
- link to email/homepage
- repositories you are a member of
- project contributions
- how many of your projects are starred
- how frequently you have worked

And a few more.  I am looking to see how to combine these facts to get a
signal score between 0% - 100% as a rough rating, which I can then publish.

My algorithm so far is quite basic so far, and only a starting point

I multiply the #followers * 3 up to a maximum of 30 followers.  e.g.

http://gitpay.org/torvalds -- 90%
http://gitpay.org/stratus -- 9 followers = 27%

I am looking for ideas on how to improve this algorithm, or maybe find a
set of algorithms people can choose from to get out a trust score (however
i am scpetical people will have time to code them).

The other problem I see is.  You could have a great reputation on twitter,
but only 1-2 followers on github that would then not be indicative of
overall trust.

One question I've been thinking about is "should older accounts be trusted
more than new ones?"

Would be interested if there were any thoughts on this.