I just got the newest version of PSE, so I'm in the process of deciding what to install. The first four things I installed were-
RadLab (definitely not free, but I do like Pioneer Woman and the Coffeeshop blog for freebies)
AutoSave actions from Wendyzine, which save in jpeg and for the web
Rock the shadows styles by Tracie Stroud
and Title Builder actions by Anna Forrest, which I sadly have not gotten to work yet, but I'm still trying.
I also came across a free credit tracking script yesterday called cvw supply tracker that might be useful if you use more than one kit when you scrap.