When you think of Google you think search but a consequence of all of those searches is some very useful trends. This is where Google Trends comes into play. With it you can enter a few different terms (separated by commas) and then the tool will return a graph of the number of search hits for each term over the last few years. Not only that you can break down the search to look at from where people are searching for these terms. I did a quick trend analysis of C#, Java, PHP and Ruby and the results are pretty interesting, especially the fact that six of the top ten cities searching for these terms are in India (although in hindsight it is hardly surprising).