What a silly thread:
Barca's ex-youth players have been mentioned, you can also add Thiago to that list.
Atletico: O. Torres, Koke, Gabi, de Gea
Bilbao: Munian, J. Martinez, Laporte, Herrera
even Real, who aren't exactly stacking their squad with youngsters, are probably at least making a good profit off their youth work, with constant player sales.
Bayern: Lahm, Badstuber, Müller, Schweinsteiger, Hummels, (Kroos), (Alaba)
Dortmund: Götze, Sahin, Schmelzer, (Reus)
Schalke: Özil, Neuer, Draxler, Mayer, Sane, Höwedes, Fährmann
Christ, there are even some mitable clubs who produced a couple of players that would be interesting for United:
Stuttgart: Kimmich, Khedira, Rüdiger, Gomez
and with 60 there is even a club in the depths of 2. Bundesliga who produced a couple of interesting players over the past years: Bender, Bender, Weigl, Volland
But yeah.. youth development is totally random and for losers!!