There are hashtag analytics services like Hashtags.org out there that can give you lots of actionable data about topics that are relevant to you or your business. You can track the volume of Twitter hashtags of your choosing on a per-hour or per-day basis. These can be tags matching your brand, tags related to your business or an event, or just of personal interest to you. You can see which users use the hashtag most often, which ones are related to the one you're tracking, and compare the usage of multiple tags.