Stunod Racing - the biggest site for NR2003 downloads today
NR2k3 - the best source around for finding real world tracks and mods
NR2003 Encyclopedia - nearly every carset ever made can be found here, including some stuff for N4 and NR2002!
NRatings - you'll want to get used to using this program, believe me!
The Pits - an old forum, not very active anymore, but there's still a lot of stuff there that can't be found anywhere else - especially if you want to learn to mod the game yourself!
NNRacing - this site was a pillar of the community since before NR2003 was even released, and while some things are broken now, there's still a ton of stuff to find here, especially cars
Big Evil Racing - Lots of things here, in particular this is the best source for finding car numbers for whatever you're trying to paint
The Bullring - home of several of the biggest NR2003 mods, from the big block modifieds, to the dirt late models, to the classic gen 6 mods of 2013 and 2015, and much more
Team Omega - if you want trucks this is where you'll get them, plus some great xfinity mods and the Winston Cup 2000 mod
Paint By RAH - the most prolific painter of base schemes in the community
Rubbins Racin - league website with lots of downloads for everything from NR2003 all the way back to NR2/99
Team SBR - They aren't active anymore, but you can find full carsets for everything from 2001 to 2016 here
Zone 15 - A classic site best known for templates, there's not a ton there but what is there is always high quality
NR2k3tracks - no longer maintained, but was always a great way to find tracks, carsets, and mods, and can still be useful for hard to find things
Armory Digital - makers of my favorite NR2003 mod to date, the ICR mod, along with some awesome tracks, carsets, and the NR2003 UI mod among other things
Action Packed Tracks - A lot of my favorite fictional tracks are here, plus some real ones that are just as good
Raceline Central - this site is as old as it looks, but there's still stuff here that can't be found elsewhere!
WildKustomCars - makers of some of my favorite tracks for NR2003 (protip: try Slinger if you haven't! If a car can't put on a good race at Slinger, it can't put on a good race anywhere. Just watch for the pace car bugs under caution!)
BB-MC - Makers of several of the most important tracks around today if you want to run a modern cup schedule
Spline Designs - small modding team with some useful things, from UI mods to tracks
Delta SimRacing - the best source for 60s and 70s tracks, cars, and mods. One of the best offline series I've done was a 1970 season using their stuff, try it!
Rolling Thunder - great source for some older tracks that have become hard to find
Brothers of Tru Racing - for the old Revamped Reloaded tracks, this is the best place to find them now
NR2k3Tracks Forum - the NR2k3 tracks forum, it's not active these days but there's still a lot here
FSB Racing - another great place to find older tracks
FSE Enterprises - great track source, with almost a complete collection of early 2010s tracks, all high quality
NR Track Designs - A group that stopped releasing new stuff a few years ago, but there are some great tracks to be found here
Talley Designs - some fun stuff here, especially for late 2010s or 1990s stuff, and a great source for soundpacks!
Stiggy's NR2003 Addons - home of the wip next gen soundpack by Stiggy, plus some paint schemes
NR2003 Racing Extremes - physics modding site, inactive lately but some great stuff here, and was the inspiration for me to get into physics modding
Sellers Gaming - a big project underway here, trying to get cup, busch, and truck physics made for every year since 1987! Don't miss it!
Zak103TV - cars, tracks, and painting resources here
Hobo Racing - tons of mods and tracks can be found here
ARCA Racing Mod - as the name says, home of the old ARCA Racing Mod
Games123 - several years of truck and xfinity carsets here
Top Notch Designs - another site with tons of stuff, an excellent source of logos and numbers for painting
R&D Racing - carsets, numbers, templates, bases, paint schemes here
AllNR2003 - most of the mods up to a few years ago are here
YouTube: Paulo Tchachalowski - he's making rFactor 2 mods now, but there are some great NR2003 downloads in his video descriptions, including IMO the definitive version of Salem Speedway
SRD archive - there's still a lot of stuff that can't be found elsewhere, thankfully archive.org picked up a bunch of it
NCRD Paintshop - A site I hadn't heard of until recently, but there's some amazing paint schemes here, this guy is talented!
Masgrafx - one of the great centers of the community, it's been in maintenance mode for years but I'm keeping the link here in the hopes that one day it might come back onlinePaulo Tchachalowski