This is the list of payware sites in my favorites, in no discernable order:
http://www.mistymoorings.com/ Misty moorings - Website dedicated to the payware addon scenery for Alaska
http://www.aeroworx.com/ - Aeroworx - Excellent payware with a few up and coming projects
http://www.anticyclone.be/active.html - Active camera website
http://aerosoft-shop.com/ - Aerosoft - Another home of some excellent payware
http://www.captainsim.com/ - Captain Sim - Some excellent commerical and military add ons
http://www.carenado.com/ecommerce/index.php3 - Carenado - Great general aviation aircraft
http://www.aussim.com.au/ - Aussim - Nice Piper available
http://www.dreamfleet2000.com/ - Dreamfleet - Home of the fantastic ATR and Beech Bonanza (the latter being the best GA aircraft I have seen)
http://www.fsd-international.com/ - FSD - Some wonderful GA and mid GA sized aircraft
http://www.fsquality.com/ - FSQuality - They have a nice Saab jet there
http://www.windrfters.com/ - Lynn and Bill Lyon's site. Very inexpensive and fun add-ons and some pretty original and odd aircraft. Bill has a great eye for fun details
http://shockwaveproductions.com/- Shockwave - Home of the Wings of Power add-on with some most drool inticing WWII aircraft
http://www.maam.org/maam_sim.html - MAAM - The best DC3 and B25 available. Also a new work in progress
http://www.precisionmanuals.com/ - PMDG - The best Commerical aircraft avail. The infamous PMDG 737NG. Also some inexpensive Beech avail.
http://www.reality-xp.com/ - Reality XP weather radar site
http://www.sstsim.com/ - The Concorde. Ive heard its the most realistic but I dont have this one as its mail order CD only
http://portal.fsgenesis.net/ - FSGenesis for terrain meshes
http://www.alphasim.co.uk/index2.html - Some decent aircraft, and while they dont claim to be the best with level of detail, they are still decent, but they do have some of the best support I have seen.
http://www.wilcopub.com/ - Wilco Publishing - Some future add-ons that look tempting
http://www.georender.com/ - Georender - Some of the best small add-on airports around. Plus their up and coming Alaska ground textures look phenominal
http://www.hifisim.com/ - Active Sky website. From what I hear its the best in weather, though I would wait until their AS 5 comes out which should be soon
http://www.vansairco.com/index.eng.php- Vans Aircraft - I dont personally own anything from them, so I cant comment
http://www.aerialfoundry.ca/payware/payware.htm - Aerial Foundry - A great F-18 by Dean Reimer
The rest of the sites in my list have already been mentioned. Just a word of caution about LAGO - their support for problems leaves a LOT to be desired.
---SaVas