Browsing around Wikipedia, I came across two fascinating bits related to writing Chinese.
The second is General Chinese, a method devised by Y. R. Chao to
represent the pronunciations of all major Chinese dialects simultaneously, and from which one can also (usually) derive the Korean, Japanese, and Vietnamese pronunciations.
In effect, GC is a reconstruction of the pronunciation of Middle Chinese, except that distinctions that have been lost from all major dialects are not bothered with.
That seems pretty nifty, if a bit impractical to read and a nightmare to learn to write correctly (since you, by definition, have to make more distinctions than your native 'lect does -- even worse than the equivalent of General Chinese for English would be, I think, since I don't think the various varieties have diverged as much).