Is there any method of adding a new datafile to a tablespace when a existing datafile is full? I know there is a mehtod to auto incrementing or resizing the Datafiles, but the problem is very large file size can pose a problem at OS level.
Not AFAIK, there is no Oracle provided method. This is where the "A" in DBA comes from.
My suggestion would be setup some monitoring scripts to tell you when you are almost full on a data file and then send yourself an email every morning indicating which tablespaces may be running out. If you want to get fancy, when your script recognizes you need a new datafile, you can automatically add it to your tablespace via some code.
Personally, I like the human intervention so I can alleviate any problem before it gets out of hand, but I'm also AR...