I can't ever recall seeing something like this, but it wouldn't surprise me if they do exist. If not, I have a pretty good idea on how it could be done if you're feeling adventurous:
Over on MTS, Morague made a
tattoo overlay mod, and even made a
tutorial for making your own.
The caveats are: it requires Seasons, and it's an object that applies an overlay to your Sims, ala tans and sunburns. The upside is though is they stay on your Sim no matter what outfit they wear, and even when they're in the shower.
That's just one idea, anyways.
