There's an area in Auridon called Tanzelwil, which I believe is filled with purple spirits. There are two quests that go along with the area (one of them being linked with the main Auridon questline) that make the ghosts neutral, but you don't have to do them to gain access to the ghosts.
if I could make another character, their name would be Cries-For-Character-Slots. AKA, I need more.
There's a town in one of the DC zones that's taken over by ghosts. You decide in the end whether to free them and let them take over the town or banish them but send them to hell or something. Don't remember which zone. Also right outside Davon's watch there are a few quests in the battlefield that's been taken over by ghosts.
I don't always drink Skooma, but when I do I go to the Southwall Corner Club. May you walk on warm sands my friends.