What you really want for a reference is someone who can speak to your strengths but also be honest about potential areas of growth. A manager with whom you worked closely on important projects fits this role perfectly.
Let's look at a slightly different scenario. You're scoring the internet job boards for your next new job and find one that looks perfect. Before submitting your résumé, you add a list of four people you would consider quality references at the bottom even though the job paying didn't specifically ask for references. One you're satisfied, you post your résumé to the job site and start the clock waiting for someone to call you for an interview.
I see two potential problems here. First, there was no mention of references being needed in the job posting. If the hiring manager needs them, they should be included as a requirement as you apply. Providing extra information only serves to muddy the waters and in the long run can create confusion. If your résumé confuses the person reading it, there is a good chance it will end up in the "no" pile.
The second concern I have is the placement of the references. By putting them at the end off your résumé, it may send the message that they are not as important as the rest of the document. If you are placing the references in you résumé because you feel they are important, make sure you put them in a place that shows that importance.