(From https://xkcd.com/)
1) Nadobranok Bot (link):
Everyday at 9 a.m., 1 p.m. and 10 p.m. he chooses random follower of my account and wish him good morning/day/evening
2) TicTacToe Bot (link) [inactive]:
Everyday from 9:15 a.m. to 6:15 p.m. he plays TicTacToe against himself
3) Kyiv Weather Bot (link):
Everyday, every hour he shows weather in Kyiv for the next hour
4) Conway's Game of Life Bot (link):
Everyday, every 15 minutes it creates new generation