This is the first bot I've ever made, and I'm pretty new to Python, so it's quite likely that my code's a mess, but at least it works! (I'll try to clean it up a bit when I learn more about the language.)
Basically, at the stage it's in now: MoneyConverterBot grabs any string in a comment that starts with '$', passes it through the converter and then replies to the comment with a table of converted results. So... nothing too special, but hopefully I'll be able to refine the code and add more features as I learn more about Python.
Here's an example of it in action: http://goo.gl/ausUlt