Here are some photos I made at Prague's Vinohrady Cemetery. This is large, fully operational cemetery, but there are probably not enough funds and it deteriorates in interesting ways. The atmosphere is really moody (not scary!) and some of the tombs would seem great to live in (after refurbishing, of course). If you want more atmosphere, it's not a problem to enter the cemetery at night (while it's forbidden and the gates are locked).
For more extreme graveyard stuff, see the famous Old Jewish Cemetery. Or something from George A. Romero.