With regards to digg, I’m using a modified version of the diggImplementor from here: http://bill2me.com/blogging/wordpress/15/wordpress-diggimplementor-plugin/
He’s working on a new version with a lot more functionality, but in the meantime, my modified version (which adds the ability for a user to submit a story) can be found here:
http://ottodestruct.com/wpstuff/diggImplementor.zip
The newest version of this plugin is actually called The digg Integrator and can be found on my site.
Version 1.1 allows for presetting a post’s topic for inclusion on digg, picking custom buttons, and incorporating the ability to digg a post from your blog rather than from digg. There’s a feed reader to show updates as well as a few other bells and whistles. If you decide to try it please let me know what you think.