Tweetoclock is a website that gives you the perfect day and time in a week to contact a Twitter Member.
On Tweetoclock you simply enter the twitter username and the website provides you the perfect time to contact your Twitter God or a chance to being read by him. Tweetoclock is based on historical Twitter time presence.
Hours are in GMT format (Greenwich mean Time), so for Montreal or New Yorkyou do GMT-5, for France GMT +1, for San Francisco GMT -8.
For example, to contact me (see above) best hour is friday at 1AM GMT or Thursday at 9:00 PM Montreal Hour.