Daychat/Nightchat websites?

[callforjudgement]

On this site, use Private Topics. (Go to the Private Topics forum and click on "New Topic". You need private topics permission; this is given to all game moderators and I think there's a way you can apply for it in other circumstances, e.g. setup reviews.)

For games run offsite, quicktopic.com is pretty good. We used to use it as standard here before private topics were invented. The main disadvantage is that the only authentication on rooms is a random string in the URL, so if someone posts the room URL publicly, anyone can look at it.