I'm really enjoying using this plugin and being able to ditch Google Analytics. However there's one feature I make heavy use of with GA + Yoast's plugin for it, and that was being able to track internal links as external.
It lets you specify what links to apply a manual onclick="" tracking parameter to, whether it's an individual link ie mysite.com/specialoffer or all links that being with /recommends/, /go/, etc.
Piwik offers something similar with "trackLink" which looks like:
So if I entered mysite.com/specialoffer then all places it was found(including in widgets) it would apply:
And I could further set a piwik goal for an external link that contains "specialoffer" and it would work(I've tested it to be sure).
I'd be really interested in seeing this feature added as it's pretty vital to what I'm doing, and am prepared to chip in whatever way I can.