Hmmm, well, thinking about it, I'm gonna break down Shadows to their basics as I understand them. I think it's probably more helpful to think along the lines of "how do I get the game to do what I want?" rather than "how do I do stuff like Wraith?" (which it sounds like you're doing anyway).
So, from what I gather, what makes Shadows cool in Wraith is a) it is a way to represent the dark side of a character other than relying on 'good roleplaying' or resources totally under his control, b) it increases the link between the players, giving a different dynamic than just "PCs and Storyteller relationship".
So, it would probably be pretty easy to come up with a fairly easy way for other players (or one specific other player) to offer your character a mechanical incentive to do 'badness' or give up on your life, or whatever 'the shadow' is representing here.
Maybe something like highlighted stats? Only instead of marking experience when you use it, you gain a +1 forward and the guy who marked it gets experience? I dunno, hard to justify 'in fiction' why X ghost gets experience for the behaviors of Y ghost influenced by Z shadow. But the dynamic might be cool.
As for a dedicated subforum, I don't really have anything to add beyond broad conceptual stuff, but maybe some others have some more concrete and helpful stuff.