TweetBeep is like Google Alerts for Twitter. Get emailed when someone is twittering about you, your company, your product, or your website!
Michael Jensen (@mdjensen) develops Twitter Tools for fun, like TweetBeep.com. I am also a co-founder of SoloSEO.com (blog), an SEO tool suite for do-it-yourself SEOs and SEO professionals. I also blog about local search at CityMarketer.com. I have created other Twitter Tools like LiveTwitting.com and TweetAnswers.