Devastation - Personal site with demos from LAN meetings. Also provides hints and a message board. - http://www.doom2.net/~dev/main.html
Lmps R Us - Personal collection. - http://myspot.neteze.com/~space/doom/lmpsrus.htm
Compet-n - Competition covering the original games and a selection of add-ons. Various categories of demos are contested. - http://www.doom2.net/compet-n/index.cgi
Doomed Speed Demos Archive - Collection of demos for both original and add-on levels, including some tool assisted demos. - http://www.doomworld.com/sda/
Public DANG - Speed contest with rankings. - http://www.doomworld.com/publicdang/
Quake Done Quick - Speed demos of Ultimate Doom, Doom 2 and Hell Revealed. - http://www.planetquake.com/qdq/doom.html