http://chess.emrald.net,,,,,,www.chesstempo.com,,,,,http://www.supreme-chess.com/chess-problems.html... these are really good if you want to improve in tactics and also this is in German... http://www.shredderchess.de/schachproblem-des-tages.html
They are NICE websites, BUT I prefer chess.com...
ADK
i dont mean for playing...they are only for studying
http://chess.emrald.net,,,,,,www.chesstempo.com,,,,,http://www.supreme-chess.com/chess-problems.html... these are really good if you want to improve in tactics and also this is in German... http://www.shredderchess.de/schachproblem-des-tages.html