All Coursera courses are deadline based. Some of the courses remove their material at the end of the course. Others, such as the database one, are later opened up as self-study but do not offer a certificate of completion.
In the case of edX, MIT's 6.00x course is strictly deadline based. CS50x allows you to take the course at your own pace as long as you finish everything before the 13th of April, 2013.
But those aren't the ones you're looking for. Udacity meets all your requirements. They have open enrollment, meaning you can join in at any time. Furthermore, they have no deadlines. As long as you complete all the problem sets and give the final exam, you get a certificate.
Here are some Udacity courses that might interest you:
In the case of edX, MIT's 6.00x course is strictly deadline based. CS50x allows you to take the course at your own pace as long as you finish everything before the 13th of April, 2013.
But those aren't the ones you're looking for. Udacity meets all your requirements. They have open enrollment, meaning you can join in at any time. Furthermore, they have no deadlines. As long as you complete all the problem sets and give the final exam, you get a certificate.
Here are some Udacity courses that might interest you:
Statistics 101 - http://www.udacity.com/overview/Course/st101 - Taught by Sebastian Thrun
CS271 Introduction to Artificial Intelligence - http://www.udacity.com/overview/Course/cs271 - Taught by Sebastian Thrun and Peter Norvig
CS373 Artificial Intelligence for Robotics - http://www.udacity.com/overview/Course/cs373 - Taught by Sebastian Thrun
Hope that helps.
Edit: There's CS188.1x by Berkeley on edX - https://www.edx.org/courses/BerkeleyX/CS188.1x/2012_Fall/abo...
It's deadline based, but I don't know whether they will remove their material at the end of the course or not.