You don't have to leave a career objective off your resume for fear of limiting yourself. You can make several versions of your resume with several different objectives. - resumes and objectives do not need to be "one size fits all." You can even tailor make an objective for each job you apply for. (Although, if you go to a career fair, where you will be handing out multiple copies of the same resume, it may make more sense to just leave your objective off.)
In some situations, you may actually want to use an object to limit yourself to save time. If you have very specific requirements (i.e. that you will not consider relocation, etc.) then it might be better to make this clear from the beginning. A cover letter can be used in this regards too instead of a resume objective statement.
