The importance of knowing what people are saying about you online, shouldn't be underestimated. By now, you should all be using Google Alerts to receive updates of your latest Google listings, or running searches on Twitter. But this is by no means extensive and there are many (free!) tools out there that you can be using to get a snapshot of what people are saying about you and, importantly, highlight the areas where you need to take action against negative comments etc..
Addictomatic is a search engine that will give you a visual representation of your presence across social media sites,including youtube, digg, google blog search and Flickr. Just pop in your brand term (or your competitors) to get an overview of where you're doing well and which areas need attention. It might be the case,for example, that it's not picking up photo or video results so you can see this is an area to focus on.
Trendistic is a useful site for tracking trends across Twitter. You can enter your search term (data may be limited for localised searches) and track recent trends to see what the level of conversation has been in Twitter. You can also drill down by day, seeing the related tweets for that time period. This is a great way to see what the overall conversation has been over certain times and highlighting any areas you may need to address.
Blogpulse is a great blog search engine as it is, but their conversation tracker is an excellent tool that can help you organise the sprawl of links and mentions about you or your brand online. The conversation trackers works by entering a keyword or seed url, then showing you a threaded view of the conversation that a particular blog post may have sparked off. I'd really recommend using this tool regularly to keep up with what's being said about you and by whom online.
Boardreader searches through forums andÃ‚ message boards for your keywords, bringing up the latest results which you can click through to, as well as graphs that will trend your results over certain time periods. I'd recommend you keep an eye on the conversations in forums,as these can be easily missed but are a valuable insight into how people feel about your brand.
Social Mention is an excellent real-time search engine, that pulls in data from a range of social media. As well as displaying the latest results, it also gives you a sentiment score of positive:negative, related keywords, reach and many other useful metrics. If you're quick off the mark with your social media monitoring, this could be a valuable way to avert a crisis before it spreads.
Facebook made changes to their search function last year, when they introduced the capability to search through public status updates. Just enter your search term and click 'everyone's updates' on the left hand side. Unless there are serious customer issues, I wouldn't recommend messaging someone privately on Facebook if you're representing a brand, but it can be an invaluable way to ascertain the sentiment around your brand, what people are discussing and areas you may need to address.
Another real-time search engine that it's worth checking out, although not quite as comprehensive as Social Mention.
This list isn't exhaustive, but is a snapshot of what I think are some of the best free tools out there. What are you waiting for? Get searching!