good thread... a while back i was trying to buy a TV and had a lot of questions that NT couldn't answer, and i didn't know what TV forums were poppinguntil i stumbled upon avsforum.
i have my own additions. this is a list of the forums i use/have used in the past. from everything i've seen these forums are the most active and are theauthority on their subject, like NT is for shoes:
forum.bodybuilding.com - Bodybuilding/Fitness. It's not just for bodybuilding, but for ALL things related to fitness and getting in shapein any way, for sports, for pleasure, for whatever. and their "General" forum (its called MISC) is pretty hilarious at times
realgm.com - All things related to the NBA. They usually break news WAY before ESPN or other outlets find out. they have forums for every NBAteam, although i usually lurk in the Wizards one.
collegeconfidential.com - this site was mad helpful when i was applying to colleges. for the HS peeps, they have all things related to collegeadmissions. and they have separate discussion forums for every college, so you can talk to other people who go there/know about the school. there are actualcollege admissions officers that post on there, so they know their stuff.
360waves.net - Forum on 360 waves/hairstyles for my black NTers. i don't go there much anymore, but back when i was trying to get my wavesright it had all the info i needed. they have dudes posting comprehensive diagrams and videos and !%*!
howardforums.net - All things related to cellphones. if you're trying to compare two phones, or if you want to mod your phone or anythinglike that, go here first.
avsforum.com - All things related to audio/visual electronics. Flatscreens, Sound systems, DVD players, HDTV, etc. and they have a Buy/Sellforum. there are some legit professional dudes on there that really know their stuff.
i'll probably add more when i think of them...