We do Naxx occasionally with the BT guilds on our server and although you completely annihilate the bosses it's a lot of fun. Most bosses keel over before they can do their abilities actually...
Anub'rekhan dies before the first Carrion Swarm (just tank the adds).
GW Faerlina dies before her first enrage (just tank the adds).
Maexxna dies right after the first Web Spray.
Patchwerk dies in like 1,5 minutes.
Grobbulus dies just as fast.
Gluth dies before first Decimate.
Thaddius is a bit harder, but just using the 2 spot tactic (even with morons who have never done it before, you'll get a few deaths but you still kill him easy before Berserk). As long as you have a few people who have done it before its a breeze. We killed him with like 20 people the first time and 2 minutes remaning or so.
Noth... dies before first port. Just offtank the adds.
Heigan dies before the first dance (although we always stop dps, the dance is so much fun and no one but a few can actually do it... so we always nearly wipe).
Loatheb... even without spores he keels over, but damn having 100% crit is a shitload of fun.
Razuvious can just be tanked while you offtank the adds, piece of cake.
You can imagine how easy Gothik is (a nice revenge for being so bloody hard at 60).
Four Horsemen... You just zerg them down one by one, ignoring the Shield Wall. Takes about 1 minute tops to kill one if everyone DPSes it. Pity that it's such a joke now, was a really good fight

.
Sapphiron is a bit buggy, but just ignore the frost res and brute force it. Dies in about 4-5 air phases maybe.
Kel'Thuzad phase 1 is a joke, so is phase 2 (its over before you realise). As long as people play semi decent (avoiding void blasts, healing frost blasts, proper spreading out, interrupting frostbolt [one shaman can interrupt these solo btw, he might miss one or two but I always interrupt it solo]) and just offtank the adds in p3.