Added: 04/15/2012
A good source because it allows the teacher considerable freedom in setting up the exercises. Personal experience with conjuguemos has taught me that the grading aspect has some flaws (unless correctly adjusted, conjuguemos will give students a total score of 100% if all questions are answered correctly--even if they only answer one question!).
¡Conjuguemos! is a self-grading, self-timed conjugating program for Spanish, French, German and Latin students. You can select which verbs to conjugate, what pronoun forms to conjugate them in, and the duration of your practice exercise. The basic tenses are present, preterite, imperfect, future, conditional, and the present and past subjunctive moods. Both the present and past progressive and perfect tenses are included also.