I have been using one flight sim or another since I first got hooked playing on an Atrai and a black and white 12 inch TV in the mid 80's.
This page has links to all the best flight sim sites I have found on the Internet.
TAP Air Portugal Virtual Airline (The first portuguese VA).
Airline Charter Enterprises
InterWorld Airlines British International
Buenos Aires Ezeiza
Club Air International Airlines
Emerald Coast Airlines
Jet Stream Travel
TradeWind Caribbean Airlines