Short tag list:

accessibility (1)
base (122)
compat32 (87)
console (149)
develop (235)
drivers (30)
games (105)
gnome (64)
kde4 (139)
kdei (2)
libs (655)
lxde (17)
network (283)
proprietary (23)
school (2)
server (26)
tcl (6)
tex (4)
themes (67)
utils (101)
virtual (76)
x86 (85)
xapps (522)
xfce (55)
xserver (317)

Long tags:

app-accessibility (7)
app-admin (24)
app-arch (22)
app-benchmarks (1)
app-cdr (9)
app-crypt (15)
app-db (1)
app-dicts (8)
app-doc (2)
app-editors (11)
app-emulation (27)
app-i18n (9)
app-laptop (7)
app-misc (46)
app-mobilephone (3)
app-office (72)
app-pda (1)
app-shells (4)
app-text (45)
dev-cpp (14)
dev-db (13)
dev-dotnet (1)
dev-embedded (16)
dev-haskell (47)
dev-java (21)
dev-lang (22)
dev-libs (142)
dev-perl (10)
dev-python (124)
dev-ruby (4)
dev-scheme (2)
dev-util (60)
games-action (9)
games-arcade (12)
games-board (9)
games-emulation (2)
games-fps (15)
games-misc (4)
games-puzzle (17)
games-roguelike (1)
games-rpg (3)
games-simulation (5)
games-sports (5)
games-strategy (18)
games-util (8)
gnome-base (36)
gnome-extra (35)
kde-base (65)
kde-l10n (6)
kde-misc (52)
kde-plasmoids (1)
lxde-base (20)
mail-client (12)
mail-mta (2)
media-fonts (23)
media-gfx (81)
media-icons (1)
media-libs (146)
media-plugins (3)
media-sound (73)
media-video (44)
media-wallpapers (1)
net-analyzer (7)
net-dhcp (1)
net-dialup (6)
net-dns (10)
net-firewall (1)
net-fs (6)
net-ftp (7)
net-im (38)
net-irc (4)
net-libs (46)
net-mail (7)
net-misc (57)
net-news (5)
net-p2p (24)
net-print (18)
net-wireless (33)
net-zope (1)
sci-libs (5)
sci-mathematics (9)
sci-visualization (4)
sys-apps (42)
sys-auth (9)
sys-base (13)
sys-boot (8)
sys-devel (24)
sys-fs (37)
sys-kernel (10)
sys-libs (44)
sys-pkgtools (5)
sys-power (7)
sys-process (7)
www-apache (3)
www-apps (1)
www-client (65)
www-misc (7)
www-plugins (10)
www-servers (3)
x11-apps (119)
x11-base (8)
x11-cursors (1)
x11-datas (3)
x11-docs (2)
x11-drivers (61)
x11-fonts (38)
x11-libs (112)
x11-misc (116)
x11-protos (31)
x11-terms (12)
x11-themes (79)
x11-utils (70)
x11-wm (17)
x11-xcbs (10)
xfce-base (22)
xfce-extra (26)