I'd like to remove curses from the Ruby standard library.
I believe the standard library should get as small as possible, and I can't find any reason to have curses except for a compatibility reason. And Ruby has RubyGems now, so it's enough to have curses.gem for compatibility.
(Sidenote, not related to this, but all of ruby's stdlib should become as modular as possible, so users could toggle on/off what components of ruby they want to have included, perhaps with rubygems able to allow for this. "gem uninstall webrick" for instance if a user really won't need that, and so forth.)