One of the more recent features to turn up in IM programs and services is to notify others when they have read your messages. This can be both good and bad. If this is something that annoys you on Facebook Chat, then you should try Chat Undetected.
Chat Undetected is a Chrome/Firefox/IE extension allows you to keep the status of your messages under wraps. This basically cloaks your message viewing and users won’t be notified when you read their messages. Since it’s a browser extension, it’s pretty convenient.
This extension allows you to somewhat nicely ignore annoying people, so they don’t know you’ve seen their messages. Of course, you could simply switch Facebook Chat off, but many people just leave that on by default.
[via The Next Web]