Today, I use TweetBeep to get alerted to mentions on Twitter, be it for vanity searches or for topics I find interesting. But TweetBeep scours all of Twitter, not differentiating between what is a good hit and what is a less valuable one. Listiti can, in contrast, search only a specific subset of Twitter users to find relevant data, and send it to your e-mail.
Setting up an Alert in Listiti
For example, I have set up a pair of Twitter lists that are interesting to me. One is "myfavoritegeeks" for real-world techies I've grown to know well, and the second is "toptechbloggers" which is a hand-selected list of people whose content I trust. I can use Listiti to watch this list for any time they mention pet projects I am interested in, such as "Pubsubhubbub", and get an e-mail immediately.
Acknowledging the Alert Has Been Set Up
So far, the alerts are not yet "real time", but they are set up to run hourly, so you will get an update containing all positive hits in the last hour. They promise digest modes are coming. This makes another great use for Twitter lists as a trusted source, whether you set up the list yourself or go to a friend of yours with good taste.