Mac: Notification system Growl has been discounted this weekend to just a buck. That's a 75 per cent discount over the usual $3.99 price tag. The latest version of Growl offers support for Apple's Notification Center, so you don't have to choose between one or the other for your notifications.
Other features of Growl include the ability to personalise the way notifications look, receive notifications in various ways (on screen, email or spoken), share notifications with other Macs, and view a history of your notifications.
Here's the link to the discounted app, courtesy of AppyFridays deals.