Where?

rss grafitti can do it via rss.. its not an elgg plugin:
http://www.rssgraffiti.com/

Here:

http://community.elgg.org/plugins/784609/1.0/facebook-service

Fernando Vega did a good job. I don't know if it works with elgg 1.8.x

Rodolfo Hernandez

Arvixe/Elgg Community Liaison

go to mod / bright theme / views / default / bright theme / css.php and look for the body tag and add something like this:

body {

         background: url(image url here);

}

flush the cache or run upgrade.php

Thanks a lot ...