Dear all,
from my experience there are two ways to participate in W3C
projects for free:
1. To become an "invited expert". A chair of a W3C invites
you to participate and you are given an official W3C account. As
an invited expert you can have a significant impact on the
group's activities because you are allowed to co-write reports
and other documents your group submits. (Some time ago I was
approached by members of the Decisions and Decision-Making
Incubator Group - they invited me to participate in developing a
decision ontology prototype).
Best regards,
Piotr Nowara