Corkboard Me is sort of Wallwisher-clone that is even simpler to use but has fewer features. You just paste virtual sticky-notes on a virtual bulletin board. One nice feature it has is by pasting the url address of an image link, the image will show up on the sticky note. No registration is necessary.
A site like this is very useful when I’m going to have students look for images in certain categories and then describe them. In the The Best Social Bookmarking Applications For English Language Learners & Other Students list (where I’m going to place Corkboard Me) and in my ELL book, I explain in some detail how to use these types of picture data sets as a language-learner lesson that incorporates higher-order thinking skills of categorization.
Thanks to David Kapuler for the tip.