I had to do a lot of line profiling (with the -l option to gprof) of some Fortran code recently and got tired of tracking through source code to find the lines that where causing problems. The line profiler gives very useful output that looks like (edited to remove some extra space):

percent cumulative  self
time     seconds   seconds  name
18.20      0.02     0.02    main (cuda-blas.cu:94 @ 401502)
 9.10      0.03     0.01    main (cuda-blas.cu:93 @ 4014c9)
 9.10      0.04     0.01    main (cuda-blas.cu:166 @ 4018c0)
 9.10      0.05     0.01    main (cuda-blas.cu:239 @ 401c3d)
 9.10      0.06     0.01    main (cuda-blas.cu:243 @ 401c91)
 9.10      0.07     0.01    main (cuda-blas.cu:318 @ 402039)
 9.10      0.08     0.01    main (cuda-blas.cu:319 @ 402060)
 9.10      0.09     0.01    main (cuda-blas.cu:322 @ 4020a1)
 9.10      0.10     0.01    main (cuda-blas.cu:321 @ 4020f0)

I wrote an IDL routine that takes the raw profile output along with the source code and creates HTML output that color codes the lines with high activity, like the following:

Get the code from my IDL library, available via Subversion:

svn co http://svn.idldev.com/idllib/trunk idllib

The mg_clineprofile.pro file is in the src/profiling directory. Call MG_CLINEPROFILE like:

IDL> mg_clineprofile, 'profile-output.txt', /all_files

The ALL_FILES keyword indicates you want output for each file listed in the profile output; you can also specify the files that you want output for via the FILES keyword.

The code is currently pretty ugly; expect changes to it coming up.