Pardon, it might have been a trivial example. I managed to find a real-world example I encountered in February this year.

The PAPI library has a utility program papi_avail which prints a table of supported performance counters. The lines may look like this:

    PAPI_VEC_SP  0x80000069  Yes  Single precision vector/SIMD instructions
    PAPI_VEC_DP  0x8000006a  Yes  Double precision vector/SIMD instructions
    PAPI_REF_CYC 0x8000006b  No   Reference clock cycles

For a course project, I wanted to turn this into a C-array like this:

    {PAPI_VEC_SP, "Single precision vector/SIMD instructions"},
    {PAPI_VEC_DP, "Double precision vector/SIMD instructions"},
    {PAPI_REF_CYC, "Reference clock cycles"},

Using :norm, this transformation can be achieved in the following way:

    :'<,'>norm I{^[eldedecw, "^[A"},

(where ^[ is a literal escape, typed CTRL-V ESC.)

Anecdotally, it is faster for me to type up such a line than an equivalent regular expression, since I use vi normal mode commands much more than regular expressions.