I suppose there is no real reason to actually use this web application (not that you have to use any I guess). Most web users generally have some form of bookmarks or favorites as a mechanism for remembering URLs. Wonderpage is a means of visually remembering URLs, with a thumbnail view of the web page being remembered in a grid/list of other such URL memories. Wonderpage is just another way of sharing your favorite bookmarks with others (or for yourself).
There is an add-on for Firefox and an extension for Chrome. You are also able to import bookmarks in an HTML file and from Delicious.
If I have to be critical, there seems to be no way of receiving much in the way of online help – FAQ, etc. It is also difficult to see just how you can link to your public page/profile.
Boomerang for Gmail is a Firefox and Chrome plugin for Gmail. It allows a Gmail user to take control of when they send/receive emails. It is currently available by invitation only – however you can apply for an invitation.