I know it's only been 10 years since the last post in this thread, but thought I'd add some stuff. Also, I noticed some of the links above go to sites that no longer exist. I've gotten back into simming quite a bit since switching to X-Plane 11. Not sure if anyone here does any flight simulator stuff these days. Doesn't look like it, but here's some useful sites to enhance your flight simming time if you choose to get into it sometime.
VATSTAR:
http://www.vatstar.com
It's a pilot training organization that teaches and certifies you for the VATSIM pilot ratings. The ratings aren't required, but the flying info is good and having a rating shows ATC that you can probably do what's expected of you in their airspace. All VATSTAR training and certifications are free, but if you sign up for a paid account, you support the continued existence of the site and get a few other perks. They also have a great Discord channel.
https://x-plane.org and
https://store.x-plane.org
The main site has news, downloads and forums. The store is where you can buy payware stuff for X-Plane.
https://www.x-plained.com/
News, reviews and downloads for X-Plane.
https://www.thresholdx.net/
News, reviews and forums.
http://www.fseconomy.net/
Adds a "purpose" to your sim-flying. Earn virtual currency for flying jobs anywhere in the world. I do this and it's ok. The best part about it honestly is it causes you to fly to places you probably would never otherwise go to in your sim. Plenty of available flights for GA and heavy metal alike.
https://datastore.swift-project.org/page/about.php
New pilot client for VATSIM. Works with FSX, FS 2004, Prepar3d and X-Plane. The setup for this new client sucks, but once you get it figured out it works pretty well. It solves a lot of the issues seen with XSquawkbox and other clients.
More to come...probably.