Some more:

Afrikaans: zoem-zoem
Albanian: bzzz
Arabic (Algeria): bezzzz
Bengali: bhonbhon
Catalan: zzz
Croatian: zzzzzz
Danish: bzzz / summ summ
Dutch: bzzz
English: bzzzz
Estonian: summ-summ
Finnish: bzzz
French: bzzzz
German: summ summ
Hebrew: bzzz (/zum zum zum)
Italian: zzzzzz
Japanese: bunbun
Korean: boong-boong (/wing-wing)
Norwegian: sum-sum
Polish: bzzzzz
Portuguese (Brazil): bzzzz
Russian: zhzhzh
Spanish (Spain): bzzz
Spanish (Argentina): bzzzz
Swedish: bzz bzz (/ surr surr)
Turkish vzzzz, vzz
Ukrainian: dzzz