[Joe Ross]

You are probably too late for an internship at a large company for this summer. Typically they will have structured programs that you should be applying for months in advance. Large companies will also screen based on GPA. In college a lot of them look for a 3.0 (and many a lot higher then that), I would expect it to be even higher for high school.

As others said, your best bet will be with smaller companies that you have personal contacts with, for example your team's sponsors, your mentor's companies, and family friends. At this level one of the main criteria will be how hard you work, so hopefully you've impressed your references. At a company without a structured program you could probably negotiate your hours. However if you want to do anything "real" you're probably looking at a 40 hour week.

Also realize that a lot of employers will google you now also. Thus it's important to make sure your online personality reflects your offline personality.