Updated July 8th, 2016
Please see the list of Good freeware scenery that is currently available for FSX/P3D. All this scenery *in my opinion and on my system, works great and is payware quality. Please MAKE SURE TO READ THE README FILES with each download, in order to avoid installation issues. Keep an eye out for this list, as it will be constantly growing. Feel free to add any airports in the comments below. Thank you.

Orbx Freeware Airport List (All Of them are great!)  
https://fullterrain.com/freeware


                         USA/Canada
KPHL- Sunskyjet Philadelphia  http://www.sunskyjet.com/sceneries
KDTW- Detroit http://www.sunskyjet.com *coming soon
KLGB- Long Beach http://library.avsim.net/download.php?DLID=184693

                                          Europe
Spain:
LESO- San Sebastian http://simzaleak.wix.com/simzaleak#!hondarribia/c1vov
LEPP- Pamplona http://simzaleak.wix.com/simzaleak#!Noain12.jpg/zoom/cblc/image_1ndu

Montenegro (Dangerous Approach Airport)
LYTV http://www.skyhighsim.com/products/Tivat_X/download

Italy:
LIRN- Napoli Capodichino Airport http://www.napulevola.it/products/scenari.aspx
LIML- Milano Linate Airport http://www.napulevola.it/products/scenari.aspx
LICJ- Palermo Punta Raisi- http://www.fsx-info.de/licj-palermo-punta-raisi-palermo-vfrals-freeware-fuer-fsx/

Cyprus:
LCPH- Paphos Airport http://library.avsim.net/esearch.php?DLID=154027&Name=&FileName=&Author=&CatID=root

Germany: 
EDAH- Heringsdorf    http://www.captain7.de/
EDGP: Frank Seifert Sonderlandeplatz   http://flusiboard.de/filebase/file/49-sonderflugplatz-edgp-oppenheim-pr3d/
EDOA: Auerbach X  http://flusiboard.de/filebase/index.php/File/44-EDOA-Auerbach-X/

Belarus: 
UMMS- Minsk International  https://www.avsim.su/f/fsx-scenarii-83/mezhdunarodniy-aeroport-minsk-2-umms-33575.html?action=download&hl=

Serbia:
http://www.skyhighsim.com/products/Belgrade-4.0 

Bulgaria: 
LBBG: Burgas Airport  http://vrcreations.webs.com/downloads
LBSF: Sofia International Airport http://vrcreations.webs.com/downloads  *need a code, please contact the developer on his website. 

Russia:
ULAA- Arkhangels  http://www.avsimrus.com/files.phtml?action=download&id=56508

                                     South Pacific/ Indonesia/ South Indian Ocean: 
FIMP- Mauritius International Airport  http://library.avsim.net/esearch.php?CatID=fsxscen&DLID=157772&Cookie=1
FMNN- Madagascar  https://mega.nz/#!W10QXDwL!OE82NC8ExExG_c9c-B7CxnDHIrQ-P70ncGA8g9ZSFZI

                                     Caribbean/ Bahamas
TBPB- Barbados International Airport http://library.avsim.net/esearch.php?DLID=153845

                                      Australia/ New Zealand:
YBCG- Gold Coast Airport  http://library.avsim.net/esearch.php?CatID=fsxscen&DLID=175183
NZNP- New Plymouth http://library.avsim.net/download.php?DLID=178576

                                      Africa/ Middle East 
OLBA- Beirut http://library.avsim.net/esearch.php?DLID=175028

G/A Aircraft 
http://frenchvfr.free.fr/download.php?lng=en&dirdnl=no&tconfig=0&id=2 ***** Very GOOD GA/// Payware quality. Must have