Full featured in python module to interface with gnusocial: https://pypi.python.org/pypi/statusnet

A younger project in ruby https://notabug.org/raito/gsruby/src/master/examples/response-bot.rb

For simple things, posting from cronjobs is as easy as http://imojito.com/post-to-gnusocial-quitter-command-line.html

To just mirror an rss feed, there is plenty of solutions like http://daemons.cf/cgit/gnusrss/about/ or http://www.tamagothi.de/2014/09/16/rss2queet/

Out of my head, I've seen !gnusocial bots engaging in conversations, watering plants, announcing tv streams, remote printing... but it would be cool to see even more of them!