Tamed pets that haven't been renamed after a month get named to something cutesy, like Mister Pebbles or Princess Lulu.
Every once in a while, when running over a solen hole it triggers a spawn of pink bunny rabbits instead of solen.
An "I'm feeling lucky!" option for recall (a la Google) where you randomly get recalled anywhere on the map.
On halloween all worn armor upon log in will be hued orange or black. Red/white/blue for north american shards on July 4th, etc. April fools - all worn armor will be sent to the bank so you log in to a naked character.
Eating more makes your character's paperdoll fatter. Not eating makes it skinnier.
GM tinkers can make cuckoo clocks - tame a cuckoo to combine with the clock, will animate the cuckoo popping out every ingame hour when placed (I've wanted this for years!)
Characters with 0 luck will slip more often (like with an icy patch), will have rain follow them, and will get randomly injured. Characters with high luck will happen upon treasure, will get surprises in their banks/mailboxes here and there, etc.
Players with the throwing skill can launch cactuses and other prickly or dangerous plants at their foes. Throwing vines will act like nets to trip up opponents, etc.