EAS had an excellent quote. Unfortunately, during one's first summer it is very competitive to get a paid position at a large firm. Generally, 1L summer jobs go to graduates at the top of their class (upper 1/4 to 1/3) from top law schools.
However, getting experience and a decent salary at a small law firm or getting experience with a judge or public agency is very valuable for the resume. Thus, I would not get disappointed if you get rejected from large firms (may be worth trying), but best to focus on smaller firms or where you have connections. Looking up alumni of your undergrad or law school never hurts, for they will often try to give you a hand when possible.
Also, it is always an excellent idea to focus upon past strengths. For example, David is wise to parlay his experience at a mortgage company into seeking a position involving real estate law.
Best of luck, know that it gets a lot easier to get a highly paid position during your second-year summer.
A lot more information on 1L summer jobs is at the law student forum:viewforum.php?f=3