Tools

iOS Apps for iPhone or iPad

• "Piano" - This is the one I use (iPhone/iPad). Just search "piano" or "piano keyboard," there are a pile of free options.

Web Browser:

• Online Pianist: It's got note names, qwerty entry, and a full-screen option.

• ToneGym: This one's kind of neat because it shows the notes you're playing on the staff as you play them.

• Clean and Simple: The Pop-Up Piano on Musictheory.net and the piano on Musicca.