When the Morrowind main quest was over, the rewards you got were Azura’s thanks and an artifact from her which was a magical ring. It had constant magical enchantments of night-eye (20 points) and restore fatigue (3 points) on self, then came with the constant repeated words from the npcs of “you’re a big hero and I don’t know how to talk to important folk like you” speech.
Even Vivec is mostly like: meh. congrats, we won’t need Ghostgate to protect us anymore.
So you are either left with nothing to do, finishing guild/faction quests, side-quests or exploring the rest of Morrowind. Or moving onto the expansions.
Ghostgate expands on the ending of the main quest as well breathing new place and purpose into the Ghostgate region. It is highly recommended that you play this mod only after you finished the main quest as it does break the main quest otherwise.
(images courtesy of Princess Stomper who is also the mod creator of this)
Ghostgate will revitalize now non-blighted Red Mountain region. It revamps the area to be lush and green instead of the desolate grey. It re-purposes the ruins you visited to be either a hotel, apartments, embassies and so on. Even the mines get revamped. One becomes a tourist spot, the other becomes an underground nightclub (with super loud music that you must constantly adjust your music volume) and the other becomes your source of income.
They even revamp a daedric ruin I believe as well. Unsure of this because I haven’t checked in the daedric ruins yet. I do know that Kogoruhn becomes a museum of ancient Dunmer civilization and of the Sixth House occupation of the ruins. The ruins of Bthanchend becomes a player owned home.
However, this is actually one of the morrowind mods that I always have to have whenever I play morrowind. I highly recommend this mod to those who play Morrowind. However be warned, it will break the main quest if you HAVE NOT finished it. I recommend you use this obviously after you done the main quest. However, when you first load it, it will provide two rings that gives you the necessary journal entries to finish the main quest. Pretty much a cheat.