Give a heads-up. Odds are you're working with other editors, whether it be a web editor for an online story or fashion editor helping organize a closet, it's important to tell not just you're boss when you're leaving. The other day I pitched a web article to an editor and later told her when my last day is due to the fact that she might not get around to editing it or reading other pitches before I leave. Even if you worked with an editor only a few times it is a good idea to give them a heads up on your departure; you never know what assignment they might give you or if the conversation is a good time to exchange contact information.
Contact your contacts. Going off of what I said about getting contact information, do so for just about everyone you work with. If you haven't already, get the interns you worked with information as well, you never know who you might work again with one day. Once you end the internship, email your boss(es) every month or so just to keep in touch. The good thing about interning at a magazine is the work you did that summer or semester will be published a few months later, a good excuse to send an email to the editor who did a piece you helped with.
Say what you want. More and more at work I hear stories about editors who waited too long to tell their bosses what they really wanted to do and the type of stories they wanted to work on. Be sure to communicate with your boss what you want from a career and how he or she many help you achieve that. It is important I have learned to remember that your boss is there to help you (and they want to help you!) Don't be scared to speak up and ensure your career goes in the direction you want it to.
Hopefully these tips to ending an internship are helpful, it can definitely be hard ending such a great experience. What are you going to do before ending your internship?
Out for now,