From The Collaborative International Dictionary of English v.0.48 :
donkeywork \donkeywork\ n.
hard menial routine work.
Syn: drudgery, grind, scut work.
[WordNet 1.5]
From WordNet (r) 2.0 :
donkeywork
n : hard monotonous routine work [syn: drudgery, plodding, grind]