2. There is Therefore a Strange Land
This is a campaign setting, which was originally planned as a kind of OSR update of Planescape, but with the Regency elements to the fore. It was billed as The Magician's Nephew meets William Blake. It has evolved somewhat since then, and I have recently been giving it considerable thought. My idea now is that There is Therefore a Strange Land is a kind of Ur-Setting. The PCs begin in a miscellaneous European city. They might be dilettantes, scholars, satanists, priests, or alchemists. One of them inherits the study of a dead uncle or aunt who was clearly Up To Something. In this study is a portal, or portals, which lead to another World or Worlds - and these can be anything the DM desires (the Forgotten Realms, Dark Sun, the Abyss, Yoon-Suin, Vornheim, the Warhammer world - or absolutely anything else). There is Therefore a Strange Land is thus a collection of tools for creating the study, the city, the PCs, the other investigating powers in the city, and so forth - the idea being that the existence of the other Worlds is also known by others, who will want to buy whatever the PCs can bring back, kill them as rivals, and so on. Moreover, since it is assumed that the PCs may become rich and powerful as a result of their explorations, there are also mechanisms for establishing power structures within the city with which they can interact. Picture a group of scholars from Regency-era London going to Athas and bringing back a cannibal halfling to sell to the Prince of Brunswick, all the while trying to avoid being noticed by their rivals, thieves, or high society, and you'll have in mind the kind of game that There is Therefore a Strange Land is all about.
3. New Troy
This is a setting loosely based on combing the Matter of Britain with Norse legend, and is a kind of tribute to Jack Vance's Lyonesse trilogy. The setting is New Troy - drawing from the old English legend that the British Isles were settled by refugees from the fall of Troy. There is a hex-map made up of 1-mile hexes, but slippage can take place into the lands of Faerie and Muspelheim. Faerie is a place where time moves much more slowly than it does in New Troy, and is the home of mystical beings and faerie shees. I call it the "Mythic Otherworld". Muspelheim is a place where time moves more quickly, and is constantly divided between the rule of frost giants and fire giants. There are also all manner of Norse and Norse-influenced evil spirits down there. It is a traditional mega-dungeon. The trick is that Faerie, New Troy, and Muspelheim all mirror each other, a bit like 3D chess: they possess the same or similar geographies, and it is possible for events in one world to influence the others. So, for instance, the castle of Kinkernadon finds a replica in Faerie in exactly the same location - Tripsey Shee - and ditto in Muspelheim. If the Lord of Kinkernadon is assassinated, the faerie prince in Tripsey Shee may also come to a sticky end. And so on. This means that the PCs can attempt to attack enemies, conduct heists, and so forth, from world to world.
4. Moons of Jupiter Planetcrawl
I've written enough about this recently: see here.
5. Fixed World [Proper title TBC]
Ditto: see here.
6. A sub-folder I have in my RPG folder on my Desktop entitled Emishi Ezo Ainu Nara Period Setting.
This is an evolution of my old 'Queen Country' idea, which I had been toying with anyway, but which I might now decide to set in an ancient iteration of Kara-Tur's 'Wa'. The PCs take on the role of officials in the budding Japanese Empire, which is spreading its tendrils into the cold North. Here there are strange hairy people called the Emishi, who worship bears, and all manner of supernatural beings, sorceresses, witches, evil spirits, and God knows what else. The PCs get XP for exploration and discovery.