Sort a file in "parallel" (note quotes!) in a multicore machine (note I'm showing 2 cores but this could be generalized to more):

    mkfifo split_aa
    mkfifo split_ab
    mkfifo sorted_aa
    mkfifo sorted_ab
    split -n2 input_file split_ & 
    sort split_aa >> sorted_aa & 
    sort split_ab >> sorted_ab & 
    sort -m sorted_aa sorted_bb > final_sorted

It's left as an exercise for the reader to determine if this actually saves any time, and if this technique could be used to implement a truly parallel sort.