Twitter is a good search engine for trends. I personally prefer TTYtter to it. This utility is extermely powerful, could deserve its own post, and cannot be resumed to simply searching. But I am just going to use it as a search engine here. Once installed and configured, you can log in and search using the command:
The interface is a bit rough on the eye, but you will get accustomed quickly. Notice that this will work with plain words but also hash-tags.