Here’s a screenshot of an iPhone app/game that practices conjugation. It’s called “Spanish Touch Trainer”. There are 2 levels: beginner and advanced. The basic concept of the game is to translate an English sentence into Spanish, verb by verb. After completing the task, you can hear an audio clip of the sentence. An added bonus is a list of verb conjugations of some common spanish verbs. It’s priced at $1.99. Here’s a review about it. I personally find it useful especially when I have down times at work to just continue practicing verb conjugations. Enjoy :)