Free options:

• Set up a Google Alert to search Blogs and Video: http://www.google.com/alerts
• Examine your inbound links in Google Analytics. Ask your web team to provide reports on who is referring traffic to your site via Twitter/Facebook et al. 
• Use www.socialmention.com. This has a widget that could be used on an intranet to show the organisation what is being said about it. 
• Use www.hootsuite.com and set up some keyword searches to monitor specific social media accounts

Paid services:

• Radian 6
• Buzz Numbers (Australian company)
• Jive Social Business Software