The "X marks" cache series to date:

"'X' Marks The Spot" (Purple_Pineapple)

"'X' Marks The Spot II - Nanny's Revenge" (Nanny Ogg)

"'X' Marks The Spot III - Witch Way Now?" (Nanny Ogg)

"'X' Marks The Spot IV - A Migrant Genius?" (Nanny Ogg)

"'X' Marks The Spot V - Look for a John" (Nanny Ogg)

"'X' Marks The Spot VI - If you can't beat them…" (tjapukai)

"'X' Marks The Spot VII - As easy as ABC" (Alboy)

"'X' Marks The Spot VIII - Or should I say XX?" (tjapukai)

"'X' Marks The Spot IX - Village’s Sharp Man?" (Brambler)

"'X' Marks the Spot X - Is that X squared? Almost" (tjapukai)