Until recently I did not know it was possible to talk to someone in your friends list while you are playing Quake Live.
When you send a message through the browser, it pops up in your friend’s Quake Live. This is already a nice feature but it is also possible to talk back while in game.
Open the console and type
/tell_buddy <name> “text here”
I find this tool very useful to drop an online friend a quick note while you’re playing.
Read these Quake Live config customization tips for many more useful console commands.