I leave irssi running in tmux 24/7, post temp file host links to images and videos all the time, and I always read and respond to the backlog when I first get on for the day in the channels I'm active in. You can also use a bot to leave a message for someone if they aren't connected currently (e.g. .tell bob I found that old video you were looking for last night. LINK) . I don't particularly want to voice chat, but I fire up Mumble as needed.