Expialidocio.us is a tool for visualizing your del.icio.us posting activity. It displays a graph of your posting activity over time. You can select a timespan from this graph, and it will show you a tag cloud weighted by just those dates.
Expialidocio.us was inspired by a posting by Jon Udell. Coming full circle, Udell has posted since posted about this application. Since then, I’ve published the sources.