Btw, here in Serbia (what you'd probably call Eastern Europe :), accordions are pretty rare (I guess they all went to Netherlands :)) other than in gypsy bands (but they rarely play in the streets other than when following weddings around), but violins (usually students), keyboards and guitars (number one, duh) are most common, but you get to hear a trumpet or a flute too. We are just classy like that (or there might be a musical school or two nearby in the part of Belgrade I see them in ;).