this is fairly specific for the folks who
* are working on a LaTeX file
* if that LaTeX file is not the master file, they are following the Vim-LaTeX suite instructions on how to compile (i.e. have a main.tex.latexmain empty file in the working folder)
* they want to compile the file but keep writing in the meantime, not having (Mac)vim taking control of the compilation process
* they are ok with launching an applescript while doing that (with Launchbar, for example)
If you fit in the profile above, here's an AppleScript (as a github gist) to do just that. In case you don't want to use latexmk, just change the appropriate line.