Music community site thesixtyone uses unobtrusive growl-like panels in the bottom right corner of the page for system alerts and messaging. Like growl or iminlikewithyou, these messages appear briefly and fade out. The effect is subtle and might be easily missed, but the addition of an ambient "pop" earcon (alert sound) tells you to look for the message. Nicely done.

1. System alerts appear in the bottom right corner, with accompanying alert sounds.