English Verb Trainer
Another app in the lineage of the German Noun Trainer and the Chinese Sign Reading Trainer. Text from the app store:
Would you like to master irregular english verbs better? Fire up the English Verb Trainer for a few minutes every day. For each verb, you get to choose between the correct past or perfect form and two wrong forms, again and again until you know them all by heart. The program trains the 150 most used irregular verbs – with a few regular ones thrown in to keep you on your toes.