Bubbleshare is rumored to be in phase of getting acquired. Bubbleshare provides the same fucntionaility as Flickr but it states 'simplicity' and 'ease of use' as the compelling reasons to its users. I happen to skim through their blog and found this one such feature that has simple usage:
"Easy upload your pictures via your Camera Phone :
1) Login to your account and go to the ‘My Account’ tab.
2) Scroll right to the bottom and click the button to generate your mobile access code. Note the email address you will use to send photos from your phone.
3) Take a snappy picture with your Camera Phone and send it to the email address you wrote down in step 2). Sorry each phone is slightly different so this step will be different on each phone.
That’s it! Email as many photos to the email address as you wish and they will be stored in your ‘My Albums’ list in an Album called ‘Mobile’"
Zooomr has an interesting background.Zooomr is a powerhouse when compared to both the above photosharing applications. It was written by 17 year old kristopher Tate and was termed 'Flickr on Steroids' when it came out. Zooomr also claims to be faster than Flickr. Here is a result of a speed test between the both.
Of course there is a fourth one , Riya which was supposed to be acquired by Google for 40 Million but did not happen as Google pulled out of the deal.Riya is not mainstream yet as they're still figuring what they are doing among so many other photo sharing sites, along with Google's Picasa.Both Picasa and Riya are in to photo recognition.
Though Bubbleshare is easier to use and Zooomr has some kick-ass features , Flickr would still be my choice. Simply because of its wide adoption. Its more likely that I will bump in to the pictures of my old ones,loved ones and lost ones at Flickr that at any other site; for now atleast.