Spirit Forges

Spirit Forges are places that allow you to exchange some of your blood to obtain artifacts (Eldrich Objects).  This can be done as often as you want, as long as you have blood to trade.  Some of the Spirit Forges can be found in Mooncaves.
FlayNorthwest of Wolf Cave
ImplodeThird Mooncave (N of Steinchencroe)
Anti-ToxinTermogent Forest (Cave to the North)
Font of PutrenscenseFourth Mooncave (S of Coorhagen)
Slow TimeFifth Mooncave (SW of Beguile cave exit)
Heart of DarknessSouth of Dark Eden
Pentalich of TarotSixth Mooncave (W of William the Just Stronghold)
Energy BankTermogent Forest
Spirit Forges also have a back entrance to them.  That way, you don't have to wait for a full moon to enter the ones that are through a Mooncave.  Most of these, usually, require that you be in some form other than Vampire and also counted as added secrets.
FlayZiegstuhl Tavern
Anti-ToxinMind Dungeon
Font of PutrenscenseVasserbunde
Slow TimeNorth of Willendorf
Heart of DarknessUschtenhiem
Pentalich of TarotNone
Energy BankMind Dungeon