Back in the day I used to make all kinds of Bionicle mocs, but most notably I made new versions of the Toa Mahri.
In my story, Hahli, Jaller, and Nuparu were bitten by shadow leeches and transformed into "Toa Trida." Meanwhile, Kongu and Hewkii were given adaptive armor so that they could take on the rest of the team. Eventually, Matoro was revived by the Ignika to help with the dire situation as well.
Here's a link to some pics of the whole "team": http://www.brickshelf.com/cgi-bin/gallery.cgi?f=324713
I also had a few other reoccuring mocs when I was younger including my "self moc;" Toa Dartho, a Toa of sonics named Filos, a Toa of "crystals" named Selia, the Makuta from '08, Arzzanhi(the fallback villain with obscure and undocumented powers), and Atequ(the similarly ambiguous guardian of light).
For some reason Arzzanhi took the form of a Tohunga at one point.
Yes, that Miru has teeth.