irssi/docs/faq.txt

Q: Why doesn't irssi display colors even when ircii etc. displays them?
A: Irssi uses curses, ircii and others don't (no, not even if ldd says they
   use it). Curses decides if terminal supports colors based on the TERM
   variable, so changing it should help. Some values to try when running
   in xterm are: xterm, xterm-color and color_xterm.

Q: Why does irssi crash when pressing Ctrl-4?
A: Most unices are usually configured to send SIGQUIT to active process when
   Ctrl-\ is pressed. Some terminals also treat Ctrl-4 and Ctrl-\ equally, so
   Irssi will die to SIGQUIT. Two ways to fix this: change it to something 
   else with stty (stty quit undef) or in irssi /SET ignore_signals quit

Q: Where's the GUI version?
A: Read http://irssi.org/?page=about

Q: How do I easily write text to channel that starts with '/' character?
A: / /text

Q: I connected to some server which isn't responding but now irssi tries
   to connect back to it all the time! How can I stop it?
A: Two ways. The "good way" to do it is with /DISCONNECT. Check the server
   tags first with /SERVER without giving it any parameters, reconnections
   are those that have tag starting with "recon" text. So most probably you're
   going to do /DISCONNECT recon-1. The other way is to remove all the
   reconnections with /RMRECONNS, easier but may remove some connections
   you actually wanted to reconnect (if you used multiple servers..).

Q: Why does irssi say "Irssi: Channel not fully synchronized yet, try again
   after a while" when I try to use /BAN etc?
A: IRC server you use is coded badly, do something like this:
     /IRCNET ADD -querychans 1 quakenet
     /SERVER ADD -ircnet quakenet irc.quakenet.org
     /SAVE
   After that /CONNECT quakenet should work properly (NOTE: when you do this
   the first time you'll have to /DISCONNECT and /CONNECT again, /SERVER
   doesn't work correctly).