If you love Twitter, you'll love TweetBeep! Keep track of conversations that mention you, your products, your company, anything, with hourly updates! You can even keep track of who's tweeting your website or blog, even if they use a shortened URL (like bit.ly or tinyurl.com). Now, how cool is that?!
A decent web app that I use to keep me abreast of Twitter when I'm not actively watching my timelines. I find it very useful since I often miss @ replies to my account. Basically, it's a kick in the pants that says, "hey! Someone's talking to/about you!"