Now for another use of Flickr Pro. If you are looking to store all your photos as backup you can do so easily (because Flickr Pro offers unlimited storage remember?). You might say there is Zooomr which offers unlimited for free of cost, then why this? Really logical. But Flickr stands apart in ways. Firstly, Flickr is much more professional with lots of privileges and settings for your own account. Secondly, it has backup of a well-known company by Yahoo. Thirdly, Flickr has lots of social and community features which often seem to be helpful and navigation is also very easy. Fourthly, Flickr has made its API codes open. So everyday developers are coming up with cooler apps which has taken Flickr to the level where it is today. Fifthly, Zooomr often has hiccups as too many users are running for its free services.
Now again some people will start crying that their favorite Picasa has been left out. Not at all, who else can compete with Microsoft and Yahoo better than Google! This would be a really close call between Picasa and Flickr based on your needs. So I suggest you this which will help you decide instantly. Let me know where you are sharing your cool snaps!