NodeXL can analyze social networks on Twitter, Flickr and YouTube, and then import the results as graph data into the NodeXL workbook. You can, for example, import a Twitter network of people whose tweets contain a specified hashtag, or a Flickr network of the people who have commented on someone's photos, or the YouTube network of videos that are tagged with a specified keyword.
Because these features access external services to obtain their data, there are a few restrictions involved in their use. For example, the Twitter features will work if you use them anonymously, but they will work faster if you authorize NodeXL to use your Twitter account to obtain the Twitter data. And the Flickr features require something called a Flickr API key, which you can obtain from Flickr. These restrictions are explained within the features' dialog boxes.