Create a custom dashlet that calls a webscript. The webscript should search all folders of type wca:webfolder and display a link for each of them. When using a javascript-backed webscript you can just call the url property of the webproject and that will the url you need. I'm not sure if there's a freemarker alternative.
A correct url would look like: /alfresco/n/browse/workspace/SpacesStore/a90dde04-16d5-4eed-a8ef-93cdf601346c
