I came across two handy applications for tracking the popularity of terms mentioned in the blogosphere and social networks. These may come in handy for your research:
Facebook Lexicon — “Facebook Lexicon counts occurrences of words and phrases on Walls over time.” It can also compare two or more words in the same chart. You need a Facebook account to use it. Full explanation and link at the Facebook Blog. There’s some keyword kinks they need to work out, but it’s definitely helpful for any Facebook-related research.
Trendpedia — Similar to Lexicon, but Trendpedia pulls info from the blogosphere. Easy to use and a bit addictive! Here’s an example search comparing blog buzz between Twitter and Facebook over the past several months: