In this thread you will find some tips to raid naxx in "hard mode" making it less boring.
Before everything you can do naxx with only 2 healers, make it much harder
(depending if your raid is full of idiots) and actually much faster because you bring more dps.
The first boss you can do something about to make it more fun(or harder) is
Spider wing:
Maexxna - Do not break the webs
You can't really do anything with Anub'Rekhan or Faerlina
Abomination wing:
Patchwerk- Tank him in frogger! have your tank/raid run around in frogger during the fight
Grobulus - once in a while, have your tank turn him to your melee, creating a bunch of slimes (make sure a tank pick them up though
Gluth - Never kill the adds (if you reach the decimate) Depending on your guild's dps this could be a very hard mode
Thaddius- Have your raid stand in 4 different groups, 2 melee (1 posivite, 1 negative) 2 ranged (1 posivite, 1 negative) split your raid in half, make it look like this during the fight : (P----N-Thadius-N----P). This will reduce your dps by alot and make it more of a challenge to kill him
Plague Wing:
Noth - Can't really do anything
Heigan - Make your ranged dance while melee are dpsing on the platform
Loatheb - Do it without spores(its an achievement too)
Military Wing:
Razuvious - I did not really know what to do here but this i found thread which i think is great.
You can also go tank the room with weapons with one of the understudy for some extra fun after the fight
Gothik - Everybody go stand on the undead side. This will *bug* the fight and gates will open after 4 waves or so... creating a huge wave of mobs (some undead too, wierd) This method is actually faster than regular since you can aoe everything much faster. You can all stand on the live side but its nowhere near as epic.
For the 4 horsemen there are many ways to do it, but you can split your group and kill them at the same time (doing an achievement at the same time)
Frostwyrm Lair:
Sapphiron: Do not decurse! make you require more dps and more healing, perfect. You can use aimed shot or mortal strike on the boss to reduce the healing too (standing in blizzardIS good for this too!)
Kel'thuzad: Make sure you pull extra "corners" in phase 1. Not only the aboms for the achievements.. the whole thing with skeletons and ghosts. Make sure you pull alot of them in a short period of time.
For phase 2 you can make groups of 5 or so that stack together to make sure the ice block hits everyone in that group.
Make sure you and your guild are having fun, because a guild thats having fun is a better guild than one which log on to raid and then log out.
But you, how do YOU do your naxx??
Sorry about my english, I know its probably terrible, because im french.