Kana Quiz allows you to practice your recognition of both hiragana and katakana.
Simply select one or more sets of characters from the settings page (available by clicking on the gear icon). An hiragana or katakana character will be displayed. Simply type in the pronounciation and get a new character.
If you get stuck, tap the info icon to get the correct answer. Simple, uncluttered interface lets your brain focus on learning the characters. No unnecessary distractions.