KanjiZ includes a few apps for learning and testing Japanese vocabulary and kanji. Most lists are based on the Adventures In Japanese series, though lists from the Genki series and a few other curated lists are being added as well.
KanjiZ runs on a Python + Google App Engine backend.
KanjiTestZ is a bare-bones lightweight interface for practicing Japanese. It allows you to select one or more vocabulary lists and be tested on them in a random order.
KanjiFlipZ is KanjiTestZ's larger, more customizable, more visually appealing big brother. It allows you to create a custom list of virtual flash cards with which to test yourself.