Mozilla requires that everyone directly contributing code to us signs a Committer’s Agreement. We have made this process easier in recent years (the most recent update was allowing people to take a digital camera shot of a signed agreement and email it in; useful if you don’t have a scanner) but it’s still more of a speedbump than we would like.
Our legal team have agreed in principle that we can have a click-through Committer’s Agreement, if it’s designed a certain way. The idea would be that a user would identify themselves as owning the email address they are going to be using, be presented with the agreement (on the page, not as a link) and click “I Agree”. This fact of agreement would be logged and stored somewhere safe. One can imagine leveraging something like Bugzilla to do the identification (because if you have a Bugzilla account, Bugzilla has already done email challenge-response with you), or building a standalone web app.
All we need now is someone to implement it, in consultation with our lawyers. Any volunteers? :-)