Janetter - Janetter is a Twitter client application. Faster, smarter, and more powerful.
Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.
Tweeticide - Tweeticide – Delete All Tweets is a commercial app that enables you to delete all of your tweets at once.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
YoruFukurou - YoruFukurou (NightOwl) is a Twitter client for Mac OS X, designed for Twitter addicts.
Better Uptime - We call you when your website goes down