22 Apr 2015 - ReplyBot will now auto-clean its database every 10 cycles. It will keep the latest (2 * MAXPOSTS) items, so disk space isn't wasted by comments you'll never see again anyway.
The most basic bot. Searches a subreddit's comments for certain keywords, and replies to the comment if it finds any. You can have multiple keyword triggers, but you only have one reply out-of-the-box.
People ask for these all the time. Be aware of how spammy they can get. If people think your bot is stupid, they will report it. Use ReplyBot as a learning tool, but do not rehash old jokes for the sake of rehashed jokes.
If you're replying to submissions, you're looking for ReplyPosts. If you want to combine them, I'll leave that as an exercise for you!