A summer job: knowing you'll never have to do this again
The great thing about summer jobs is being able to "job shop" different professions. Although most of them only last a few months, it gives you the enough experience to decide whether or not this is something you would want to do for the rest of your life (or a good 40 years of your life). If it's an internship, or a job in a field that you may want to go into upon graduation, the summer is the perfect opportunity to decide what you like and what you really don't like.
If you're majoring in business, and you get a job as an office assistant, you really get the feeling of what it would be like to work in that field--or that it is time to change your major. Of course each field is broad enough that one experience can't fully show the entire field, but it does give you a pretty good idea as to whether or not you want to go into it. For myself, working in a customer service job makes me realize that I really want to help people as much as possible, because it's a great feeling to make somebody's day, but it also makes me realize that in customer service, people treat you like dirt. If you can't give them everything they want, they often make you feel like a small, horrible person. Thanks to my summer job, I have been able to narrow my search of what I want to do upon graduation: be able to help, but also have enough clout to not be yelled at if the business I work for doesn't have an amenity the person wants.
So, to sum up my ramblings here, summer jobs are a great opportunity to discover what you like--and what you don't--and shouldn't be taken too seriously, because, after all, they are for only the summer.
Well, how come you say you will when you won't?
Say you do, baby when you don't
Let me know, honey, how you fell
Tell the truth now, is love real?
so, aw, aw
Well, honey don't
Well, honey don't