Currently only on RK1 though...
MemoBot has finally been completed (yay..) - if you've ever visited IRC, you can guess what it does For those who haven't; MemoBot allows you to send memos to other players. Yeah, I know, you can send people tells when offline and those are stored until that person logs in. After which they all get dumped to the screen and won't ever be seen again.
MemoBot allows memos to be stored and deleted at your own leisure, so it's quite useful to send people a reminder about something, or send your friends some tips on where to find the fat loot - and they can just keep the memo around until they get tired of looking at it
/tell memobot help will get you a list of commands
Enjoy!