If you use Growl for system-wide notifications, then you may want to check out the MailMe notification. This is only useful for people that reserve Growl for important notifications or it will REALLY irritate you. WARNING: Dial down your notifications in subscribing apps first.
Once turned on, you give permission for Growl to send emails. When a Growl notification happens (like an IM chat starting in Adium), a message will be sent to the nominated email account.
This has come in handy when I've been away from my computer (like at lunch, in a meeting, out) and want to know what my system is up to. I have an iPhone so I get email everywhere.
Use it as you will - but dial down your notifications to things you really want to know about or it will drive you nuts.