I just spent a day trialling Chartbeat, which is a very slick, paid real-time stats service, and then removed it because the differences over what Piwik and Google Analytics give me simply wasn’t enough to justify paying.
Eye-candy aside, there are some nice features to Chartbeat that I’d love to see in Piwik:
[li] A dashboard widget showing how many people are on my site right now
[/li][li] A dashboard widget for social mentions, aimed at twitter & facebook at least
[/li][li] Email/sms alerts based on site traffic (although their current incarnation is mostly aimed at telling you that you’re going to need to change payment plans soon)
One surprise was that Chartbeat saw more visitors than Piwik does in real-time, but when visitors seen by both appeared first in Piwik’s dashboard. Is this only because, of 2 pieces of code included on each page, Chartbeat has one piece of code at the top of each page?