I forgot to mention that Toradora features an all-star cast: Rie Kugimiya as Taiga (not sure what her best role is... of course many know her as Louise of ZnT, but I think her Futaba of Shingu was rather nicely done), Ai Nonaka (Mikan, Shippon), Rie Tanaka (I think she plays the intimidated teacher -- a rather minor role, strangely), and Yui Horie (goes as far back as Multi in To Heart). The all-important role of Ami is given to Eri Kitamura, about whom I know exactly nothing, but she seems to do very well. I do not believe for one second that such a constellation could be produced by random auditions. It must be by design, although to what end I cannot tell. I'm not very seiyuu oriented.

P.S. I find it strange that the premier seiyuu blogs, j1m0ne and Hashi-hime, ignored the Toradora's cast as a whole, with the latter merely observing that Rie Kugimiya gets typecast.