Okay, so far I have seen at least three colors that would make it good in all three themes, hexadecimal values:
Hex={CC,66,00}
Hex={CC,99,00}
Hex={00,66,66}
It seems they would be even better if used in bold type, but it would be up to you, also there is an option:
Have it the same colors of links on each theme, ither visited or unvisited, but that would ask for another thing, qutations as separate paragraphs.
Anyway I might keep experimenting, but i think those, especially the mustard ones would be okay and not very far from any of the themes.
Edit: By the way, morrus, your title is on the pirate's day yet.