One thing you could try using is ITA Software:
http://matrix.itasoftware.com/cvg/dispatch/prego
You can't just type "any European city" in the destination field, but you can put in multiple airports separated by a semi colon (e.g. AMS;ARN;ATH;BRU;BUD;CPH;FRA;HEL;LIN;LIS;PAR;VIE) instead of punching them each individually.
And of course there are the gateway maps on FareCompare:
http://www.farecompare.com/maps/comp...?departure=DSM