nice idea, but I think the options for chatting should be pre set otherwise it will get dirty if some one loses his temper.
Option would be you can choose from different phrases like :
good game !
meet me in an hour for test game revenge !
Any player to sell ?
wanna chat ? meet me at the top eleven forum and open a thread with your team name.
your team is really good, congrats !

and so on and so on
not sure if it is possible but would be cool if there would be a kind of communication with active players.

cheers