In my humble opinion, Fencer, Spirit, and Bailey are spot on with their attitudes about jobs. No matter how you put it, JROTC/CAP/Boy Scouts/etc. leadership roles just aren't the same as a real job. I'm not saying they're not important (obviously they are!), but work provides even more of a "real world" experience that's hard to get any other way.
For example, work provides an opportunity to get a special kind of interpersonal skills. True, JROTC, etc., will teach you how to communicate effectively with others. But when you work a job, you learn how to effectively solve those vexing little problems which are frequently not included in high school activities. What if a coworker is having a bad day? How do you cheer him/her up and make a friend in the process? Trust me, it's not the same as coaching an unmotivated cadet, especially if the coworker in question is 35+ years older than you(!). You learn how to manage time, how to work with different types of people, and how to be accountable for your own actions (even more so than in HS activities). Oh, and Fencer said it best: it's GREAT to be earning your own allowance!
Again, this doesn't mean that not having a job will necessarily harm your application, but working a job certainly won't hurt it! If you can fit it in somehow, I would certainly consider looking for employment. It's really a great way to learn life skills that will pay dividends down the road, regardless of your career choice.