WikiMatrix et al
The WikiMatrix site is not an official part of the splitbrain universe but was built by me at my day job.
WikiMatrix allows you to compare various Wiki engines by feature. You can select the engines you're interested in and get their features listed in a side-by-side table. A really nice feature is the possibility to mark (flag) features you're interested in most and then filter the comparison table by them.
The comparison features were written by me, for the tight forum integration PunBB was chosen.
Meanwhile WikiMatrix was accompanied by a few more comparison portals:
More portals are planned.