localhost ~ $ equery u x11-base/xorg-server
[ Searching for packages matching x11-base/xorg-server... ]
[ Colour Code : set unset ]
[ Legend : Left column  (U) - USE flags from make.conf              ]
[        : Right column (I) - USE flags packages was installed with ]
[ Found these USE variables for x11-base/xorg-server-1.1.1-r4 ]
 U I
 - - 3dfx                      : Adds support for 3dfx video cards to XFree86. S
ee: voodoo3
 - - aiglx                     : Includes extra AIGLX patches that allow compiz
to function
 - + debug                     : Enable extra debug codepaths, like asserts and
extra output. If you want to get meaningful backtraces see http://www.gentoo.org
/proj/en/qa/backtraces.xml .
 - - dmx                       : Build the Distributed Multiheaded X server
 + + dri                       : Enable direct rendering: used for accelerated 3
D and some 2D, like DMA
 - - input_devices_acecad      : <unknown>
 - - input_devices_aiptek      : <unknown>
 - - input_devices_calcomp     : <unknown>
 - - input_devices_citron      : <unknown>
 - - input_devices_digitaledge : <unknown>
 - - input_devices_dmc         : <unknown>
 - - input_devices_dynapro     : <unknown>
 - - input_devices_elo2300     : <unknown>
 - - input_devices_elographics : <unknown>
 - - input_devices_evdev       : <unknown>
 - - input_devices_fpit        : <unknown>
 - - input_devices_hyperpen    : <unknown>
 - - input_devices_jamstudio   : <unknown>
 - - input_devices_joystick    : <unknown>
 + + input_devices_keyboard    : <unknown>
 - - input_devices_magellan    : <unknown>
 - - input_devices_microtouch  : <unknown>
 + + input_devices_mouse       : <unknown>
 - - input_devices_mutouch     : <unknown>
 - - input_devices_palmax      : <unknown>
 - - input_devices_penmount    : <unknown>
 - - input_devices_spaceorb    : <unknown>
 - - input_devices_summa       : <unknown>
 - - input_devices_synaptics   : <unknown>
 - - input_devices_tek4957     : <unknown>
 - - input_devices_ur98        : <unknown>
 - - input_devices_vmmouse     : <unknown>
 - - input_devices_void        : <unknown>
 - - input_devices_wacom       : <unknown>
 - - ipv6                      : Adds support for IP version 6
 - - kdrive                    : Build the kdrive X servers
 - - minimal                   : Install a very minimal build (disables, for exa                                                                                                 
mple, plugins, fonts, most drivers, non-critical features)
 + + nptl                      : Enable support for Native POSIX Threads Library                                                                                                 
, the new threading module (requires linux-2.6 or better usually)
 + + sdl                       : Adds support for Simple Direct Layer (media lib                                                                                                 
rary)
 - - video_cards_apm           : <unknown>
 - - video_cards_ark           : <unknown>
 - - video_cards_chips         : <unknown>
 - - video_cards_cirrus        : <unknown>
 - - video_cards_cyrix         : <unknown>
 - - video_cards_dummy         : <unknown>
 - - video_cards_epson         : <unknown>
 - - video_cards_fbdev         : <unknown>
 - - video_cards_fglrx         : <unknown>
 - - video_cards_glint         : <unknown>
 - - video_cards_i128          : <unknown>
 - - video_cards_i740          : <unknown>
 - - video_cards_i810          : <unknown>
 - - video_cards_impact        : <unknown>
 - - video_cards_imstt         : <unknown>
 - - video_cards_mach64        : <unknown>
 - - video_cards_mga           : <unknown>
 - - video_cards_neomagic      : <unknown>
 - - video_cards_newport       : <unknown>
 - - video_cards_nsc           : <unknown>
 - - video_cards_nv            : <unknown>
 - + video_cards_nvidia        : <unknown>
 - - video_cards_r128          : <unknown>
 - - video_cards_radeon        : <unknown>
 - - video_cards_rendition     : <unknown>
 - - video_cards_s3            : <unknown>
 - - video_cards_s3virge       : <unknown>
 - - video_cards_savage        : <unknown>
 - - video_cards_siliconmotion : <unknown>
 - - video_cards_sis           : <unknown>
 - - video_cards_sisusb        : <unknown>
 - - video_cards_sunbw2        : <unknown>
 - - video_cards_suncg14       : <unknown>
 - - video_cards_suncg3        : <unknown>
 - - video_cards_suncg6        : <unknown>
 - - video_cards_sunffb        : <unknown>
 - - video_cards_sunleo        : <unknown>
 - - video_cards_suntcx        : <unknown>
 - - video_cards_tdfx          : <unknown>
 - - video_cards_tga           : <unknown>
 - - video_cards_trident       : <unknown>
 - - video_cards_tseng         : <unknown>
 - - video_cards_v4l           : <unknown>
 - - video_cards_vesa          : <unknown>
 - - video_cards_vga           : <unknown>
 - - video_cards_via           : <unknown>
 - - video_cards_vmware        : <unknown>
 - - video_cards_voodoo        : <unknown>
 + + xorg                      : Build the Xorg X server (HIGHLY RECOMMENDED)
 + + xprint                    : Support for xprint, http://www.mozilla.org/proj                                                                                                 
ects/xprint/