Cool! You should release it as a hack! I'm not too handy with PHP (yet)
I'll check out that bot asap.
The invite feature basically displayed a list of people online to the user in the chat. It gave them the option to choose who to send an invite to. The invited user would recieve a message (like the PM notification) to go to the chat.
You can see my old board here:
http://johnsworld.com/cgibin/mhs/ultimatebb.cgi (click on the chat)
Notice how the chat is integrated very cleanly! It would detect the users online by pulling from the 'Who's Online Hack'. It didn't work very well however, because it could only count the user if they were using jIRC on the link: ultimatebb.cgi?ubb=chat . It also wouldn't count them if they were in the chat for more then 15 min. (the assigned 'online time' period) The way you have it setup would solve that problem and create a new hack for vB.