Sightseeing in the 40K universe

I find myself often becoming very confused as to the location of important places in the Warhammer universe.  I made myself a quick cheat sheet:

Segmentum Solar (Center)

Holy Terra
Cthonia (Luna Wolves) *
Nikea
Necromunda

Segmentum Ultima (East)

Chemos (Emperor's Children) *
Chondax (White Scars)
Catachan
The Maelstrom
Badab
Gorkamorka
Nocturne (Salamanders)
Ultramar (Ultramarines)
Tau Empire
Baal (Blood Angels)
Nostramo (Night Lords) *
Nuceria (World Eaters) *
Prospero (Thousand Sons) *
Olympia (Iron Warriors) *
Laeren

Segmentum Tempestus (South)

Deliverance (Raven Guard)
Barbarus (Death Guard) *

Segmentum Pacifus (West)

Sabbat Worlds (Tanith)
Colchis (Word Bearers) *
Murder
Krieg

Segmentum Obscurus (North)

Eye of Terror
Medusa (Iron Hands)
Cadia
Caliban (Dark Angels) *
Fenris (Space Wolves)
Calixis Sector (Dark Heresy RPG)
Gothic Sector (Battlefleet Gothic)
Scarus Sector (Eisenhorn and Ravenor)
Arkona (Eternal Crusade)
Istvaan System *

* indicates currently a dead world in 40K