Yiddish Slang Dictionary
This app is worth the US$1.99. Nothing I could write could be better than the description: "Oy vey, stop your kvetching. You've found the Yiddish Slang Dictionary, to help you shmooze and kibitz. Be warned though, this app contains some words not fit for your bubbe." Not as deep into Yiddish as I would have liked but covered all the basic slang my parents' generation uses.