Menucolors is a patch that allows you to colorize individual rows on a menu based on what regular expressions match its text. The patch was written by paxed and can be found here. You can color the inventory menu, the spellcasting menu, the enhance menu, the options menu, and more. Menucolors are currently only supported in a terminal and (partially) in the Windows GUI.
For example, you could color all blessed items bright cyan, all cursed items bright orange, and all uncursed items dim green. From there you could underline dangerous items (loadstone, wand of cancellation, etc.), make the Amulet of Yendor magenta, all gold yellow, and so on, until you're satisfied.
The menucolors patch also supports globbing instead of regular expressions; the resulting menucolors are far less powerful, but are more portable.
The menucolors are applied top to bottom, and each successive match replaces the colors and attributes. Unfortunately, there's a bug in that setting an attribute (bold, underline, etc) resets the color of a line, and vice versa. You can work around this by setting color&attribute, but that's not a very general solution.
There is a precompiled binary of NetHack 3.4.3 Windows GUI and TTY with menucolors available for download here.
OPTIONS=color,menucolors MENUCOLOR="uncursed"=green MENUCOLOR="blessed"=cyan&bold MENUCOLOR="cursed"=orange&bold MENUCOLOR="loadstone\|wand \(of\|called\) cancellation"=underline MENUCOLOR="Amulet of Yendor named"=magenta # color only the real Amulet MENUCOLOR="gold piece"=yellow MENUCOLOR="[a-zA-Z] - [a-zA-Z ]+[ ]+[0-9]+\*[ ]+[a-z]+[ ]+[0-9]+%"=magenta # forgotten spell
and here is an example that uses globbing, that is, only ? and * wildcards.
OPTIONS=color,menucolors MENUCOLOR="* cursed *"=red MENUCOLOR="* unholy *"=red MENUCOLOR="* blessed *"=green MENUCOLOR="* holy *"=green