Guides published by Egosoft (patch notes are here)
Rebirth v1.25: features video.
Rebirth v1.30: Upkeep Missions video.
Rebirth v2.00 can guide is here.
Rebirth v2.50 Diplomatic Aid missions are explained in this video.
Rebirth A v3.00 feature guide is here.
Rebireth v3.50 Flight Assist OFF guide is here.
Guides written on the forum (players and Egosoft)
Boarding by XenonSurf (link).
Barding trick with Traitor drones ("XenonSparky Maneuver") by Sparky Sparkycorp and XenonSmurf (link).
http://forum.egosoft.com/viewtopic.php?p=4543757#4543757
Hidden containers by Snafu_X3 (link).
Hidden ships by euclid (link).
Keyboard Command / Hotkey List by Ameer Nuub (link).
NPC Small Talk & Trade Agents by Sparky Sparycorp (link).
NPC ships and Trade Reservations by Bunit! http://forum.egosoft.com/viewtopic.php?p=4555941#4555941
NPCs for hire by euclid (link).