What WP plugins work for individual blogs within WPMU

I am having a hard time finding WP plugins that our individual users can use on their blog. I tried a few that were suggested and they do not work within the WPMU platform for individual blogs. (ie. Contact Forms: http://wordpress.org/extend/plugins/contact-form-7/
Social Media Widget: http://wordpress.org/extend/plugins/social-media-widget/ ) neither of these work in the WPMU environment.

What are some plugins that people are installing for their users that work ? We want to offer them some "perks", including a few plugins, for coming with us as opposed to a free blog at Wordpress.