Unusual and important, but not perfect
This is the only app I know of that focuses on letter SOUNDS, not names. There are plenty of apps that name the letters, but getting the SOUNDS right is critical for learning to read. Granted, the sounds arent always voiced the same when said alone as they would be in a word, (and here they pronounce the s as an s, but then it sounds like a z at the end of the word) but at least this app moves through the process: the individual sounds separately, then said one right after the other, and then blurred together. Not perfect, but closer than many other letter apps out there. 5 stars for being unique.
Chakids about
PocketPhonics (basic edition), v2.2.1