In many cases a group based workflow is more appropriate than an individual based workflow, so here's a group based version of the OOTB Web Site Submission workflow.
To install it as an extension, extract the attached zip file into the alfresco/extension directory then open up the web-client-config-custom.xml.FRAGMENT file and copy the contents into the web-client-config-custom.xml file. The first block of text (the WCM UI config) needs to be copied to the web-client-config-wcm.xml file in the Alfresco webapp due to the bug described in WCM-786.
If this is merged into the official Alfresco distribution it would probably make sense to move the content model etc. back into the wcmwf namespace (implementing extensions within an existing namespace can be a bit fiddly, so I used a new namespace). That may also allow for some simplification of the content model and property sheet configuration.