My current simplistic (and very dumb!) solution that I've used for power-law type distributions — like HN virality, for instance — is to count the number of days between viral events, and then subject that to process control.[1] I basically take Wheeler's approach to chunky data and use that for J-curve type data, which tells me if the behaviour of my 'HN virality process' has changed.
I'd be very interested to learn of other approaches.
[1] HN traffic for commoncog.com displays routine variation most weeks with an Upper Process Limit of 192 and a Lower Process Limit of 0, unless one of my articles hit the front page, at which point I get 11-16k additional uniques).