Which of the common sorting algorithms can be parallelized?
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Parallelism can be achieved by using  pipeline of processing units or using multiple processor link.

For comparison based sorting lets take an example of quick sort , in quick sort after we find the pivot then we can process two parts in parallel.

quicksort(A)
if |A| = 1 then return A
i := rand int(|A|)
p := A[i]
in parallel do 
 L := quicksort({a : a ∈ A | a &lt; p})
 E := {a : a ∈ A | a = p}
 G := quicksort({a : a ∈ A | a &gt; p})
return L ++ E ++ G


Another example we can take is of Radix sort which does not directly compare keys to determine ordering.The basic radix sort algorithm (whether serial or parallel) examines the keys to be sorted one “digit” position at a time, starting with the least significant digit in each key.For implementation in parallel see this tutorial Parallel In-Place Radix Sort