Datacities was recommended here
http://moodle.org/mod/forum/discuss.php?d=431
But there are some not so good rumours about datacities at
http://www.webhostingtalk.com/showthread.php?s=&threadid=107906
http://www.webhostingtalk.com/showthread.php?s=&threadid=77754
Please also see
http://moodle.org/mod/forum/discuss.php?d=1870&parent=7962