So, the bot contest over at omni has inspired me to make a bot I've been meaning to make for quite some time: MineBot! It plays minesweeper. It's up right now (though keep in mind as I work on it it will go down). You can play through DCC:
/dcc chat MineBot
The gameplay should be pretty straight forward, you just tell it which row and column you want to "click" on, and it goes from there. I'm thinking of adding other games as well. I'm also going to make it so it can hopefully do private messaging as well.

Since my client is currently being too uncooperative to work with DCC chat, I must congratulate you without actually having tried this yet. Does it spit out an ASCII image of the board each time, or do something more devious with letting you keeping an image of the board in your own memory? Since you said you were concerned about it flooding itself off the IRC server if it used PMs, I am going to assume that it spits out an image of the board.

It does indeed just spit out some ASCII. Once I'm back home I'll work on making it work under PM (with some sort of limiter) so that you can try it out without DCC. I think that'll make it more accessible.

Source is available if anyone wants to download it:
http://merthsoft.com/MineBot.zip