I quit watching the first Negima in part because I couldn't keep all the characters straight. So I've made a
character chart for the new anime.
The chart has a pic of each student, names their
seiyuu, links to the ANN page for the
seiyuu (or to the entry in the
hashihime seiyuu gallery, if I have one there) and gives a brief description of the character, taken from the official site for the new anime. Just making it has helped me a lot.
(cross-posted to the voice-actor appreciation thread)