I don't think that would be ideal. I think there are plugins that can be hard to find games for. I think a possible solution would be some sort of network people could subscribe to and communicate.
For example, if you played star wars, everyone who wanted in could subscribe to something like twitter. One person could tweet something like "Looking for a game of star wars" and everyone who was on the list would be instantly sent the broadcast on a variety of devices.
Ideally, there would be enough people that played all the plugins so people could find a game whenever they wanted, but less popular plugins can't seem to do that now.
I'm not sure a web app broadcasting the current player list would help. I mean, there isn't much difference between that and staying logged in with lackey.
I think it would be cool if existing networks could be used. Maybe a Facebook group, or twitter, or something else. I'm open to ideas.