While there have been attempts to apply the instant alerts concept to Twitter, we haven't seen an application get the formula completely right yet. Perhaps we spoke to soon, as we just discovered Listiti, a new web-based application that promises to do one thing: send you email alerts whenever tweets from specific Twitter Lists match your specified query.
The Listiti implementation is both practical and genius. We've been talking about Twitter Lists as one of Twitter's most important features, providing necessary context, and allowing for a variety of creative use cases. Listiti takes Twitter Lists one step further with an extra layer of convenience, so you can keep your eyes on the important tweets in Twitter Lists, without having to be on Twitter all day.
Setting up a Twitter Lists alert is dead simple. Simply identify the List you'd like Listiti to watch, add in keywords to watch, and enter your email.
Listiti also gives you the ability to promote your Twitter Lists, making it convenient for you to direct Twitter followers or friends to a page that is pre-populated with your List name. Here's how it works: use this structure and replace the necessary fields: http://listiti.com/YourTwitterAccount/YourListName. So if you want to start alerts for our Mashable list, you would just go here: http://listiti.com/mashable/mashable.
A few things to note. Listiti is fresh out of the gate, with the developer Xavier Dammn [@xdamman] posting a request for feedback on Hacker News earlier today. Admittedly, Listiti isn't as fully developed as it could be, which means you'll only get alerts hourly - you can't use OR queries - and you can't subscribe to an RSS feed of the alerts. We hope to see this one man shop find some funding so he can continue to build out the service.