An excellent tool for learning NATO / ICAO / ITU phonetic alphabet (a.k.a. International Radiotelephony Spelling Alphabet)

Features:
Generates random letters
Shows the corresponding NATO / ICAO / ITU codes
Speaks the codes using the Android voice synthesiser
Records your voice then compares it with the correct codes
The number of letters randomly generated is configurable.
Text color and size is configurable
Multiple backgrounds to choose from