C# - Creating A Google Labs-like Extension Feature?

In this application I'm working on, I have an extension system based on static events. The whole idea is taken mostly from the (very cool) extension system created in BlogEngine.NET.

Essentially, on Application_Start, an extension instance is created which hooks to static events on classes in the application. Take for example an extension that censors blacklisted words from, say, a forum message before displaying it to the page; When a ForumMessage.OnDisplaying event is triggered, the extension would take the ForumMessage sender object and replace blacklisted words with gibberish.

Example:

static class WordBlackListExtension {
private static string[] _blacklist = new string[] { ... };
static WordBlacklistExtension() { ForumMessage.OnDisplaying += DoWork; }
private static void DoWork(object sender, EventArgs e) {
// Do some blacklist filtering...
((ForumMessage)sender).Body = ...;
}
}

However, since there is only one instance of each extension in the App Domain, it occurs to me this only works on a system where there is a single, system-wide configuration for each extension. But what if I wanted per-forum or per-user control over those extensions, like in Google Labs? Per-forum blacklist, or per-user ability to enable/disable the extension? I would have to pass additional information to the extension.

So here's the part I can't wrap my head around - Assuming I have a fairly complex object model (therefore doing something like ForumMessage.Forum.etc.Config is bad practice);

How would you recommend to pass that information to each extension? Should each extension retrieve its own config? Maybe pass some kind of context object through the EventArgs? Where can I determine which forum's config to retrieve?