Microsoft has a summer internship program specifically for high school students.
It is open to current juniors and seniors with a demonstrated interest in technology, knowledge of email and Word, and a basic grasp of HTML, Visual Basic, or other programming language (preferred).
Applications are due by March 11. If you are selected, the full-time job is for 8–10 weeks starting in June.
Details are here: Microsoft High School Intern Program.
Let me know if you are interested; you’ll need a recommendation from a teacher, as well as a resume, etc.