I just found this couple of days ago

Sending a user a message when he's offline ! When the user get online, he will receive the mesage.

First send an IM to "AIMOfflineB1", type in anything like "."

then another IM box will pop-up...the message will be

"AIMOfflineD4: What screen name do you want to send an offline message to? ( Type C to cancel )"

Then type in the screen name you wish to send the message to ! Like CrashCourse01 (Raion)

"SysAdmnOP: CrashCourse01
AIMOfflineD4: What message would you like to send? ( Type C to cancel, type R to activate a return receipt )"

Type in the message like "Whats up lamer"

SysAdmnOP: whats up lamer
AIMOfflineD4: That message will be sent to crashcourse01 the next time s/he signs online.

The user will receive the message when he gets online.

www.aimoffline.com is the official site.

I didnt find anything wrong with this (getting spam afterwards or something) so its looks good. It's a nice trick too.

Maybe this should go into Tips & Tricks ?

Well, thats it !