I was thinking maybe would be a nice feature, sometimes.
Every time you joined such IRC chat room you would have to send bitcoins and if you were kicked and wanted to enter the room again you would have to pay again. And that money would be shared to all users in the chat room or to the channel ops.
What do you think?

Im sure coding a bot for this would be simple enough

Essentially, you could run a bitcoin client on the same server as the bot, have it generate an address and attach it to each nick, as soon as the client receives the BTC, the bot would know what to do.

You could probably set up a bounty for someone to build this for you

Maybe the fee should change according to the number of users on that room.
The more users it had, the higher the fee.
It could better suit integer division.

Freenode IRC does mean Free.

http://freenode.net

No no, just a quick socket bot. People could join a lobby channel, receive an address from the bot (who happens to be opped in the pay-per-entrance channel), and once the bot receives payment, he lets the person in. Alternatively, the channel could be +v, and you have to pay for +v status. Also, it could be done in such a way that you pay per minute, rather than per entrance. Plenty of ways to do it. I personally like the +v idea; it sets a monetary incentive to not spam.