It's a tool that can track when a tag is used. So if we used #PPCalert, a tweet might go like:

#PPCalert trollfic in Harry Potter, Becoming Female by venusgod
And then include a link.

If we use a website called Twubs, www.twubs.com/PPCalert/ will always have a list of badfics that we can then discuss via Private Tweets.
www.twubs.com/PPCalert/embed/ can also embed the feed into a webpage, so we can put it on the Wiki and/or personal blog.