Current size of the #curl(1) man page: 6,232 lines.
It documents all 258 command line options.
@hyc @bagder this got me thinking about what would be an appropriate relationship between the length of source code and the length of the corresponding man page. Having thought about that for a minute I now think there is no answer really, it all depends on the kind of tool the program tries to be. In some cases it would be laudable to have a short man page, "do one thing well" and so on, but I think in other cases it could be perfectly fine to have a man page even longer than the source code.