Here is the full list of all 11 Spooky Ghosts Dot Com achievements.
Kill the crows locked up in the basement
Find and pet all of the cats!
Have more than 500 candy at one time
Beat the game without dying once
Defeat The Punk
Defeat the Jail-o-Lantern
Defeat the Frog Witch
Acquire a ghost buddy
Defeat the Feast Master
Finish the game
Keep a leaf airbound for awhile