One of my friends made an AIM bot designed to provide you information of the winter parking ban details of each street in Worcester (pulls from the
Worcester website) or to notify you via e-mail, AIM, or txt whenever a winter parking ban takes effect. It can parse words for rudimentary conversation as well. Appropriately enough, the screen name is "ParkingBan". He had had plans to make it nationwide for major cities in the far future, though that requires significant effort of course. He lives in California now so I think the bot project might be abandoned since they don't often have variable parking bans (though it remains online for us Worcesterites).
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They can be put to extremely good use when programmed properly. Another friend is working on a bot to control his G5 remotely from anybody's computer.
I used to have a conversation bot on my computer called FeBOT. This was long before the days of consumer high-speed internet. It was a program you installed on your computer and .. just .. conversed with it ... was fun for the easily amused.