Were I a high school senior again (and limiting it to courses that would be considered appropriate for a yeshivish setting — no archaeology, anthroplogy, etc.), I suppose you could include any of the following:
Forensic Science (as mentioned above)
Graphic Design
Photoshop
A “fun” slant on statistics — for boys, for example, you could give a course on “Advanced Baseball Statistics.” For girls, I suppose, you’d need to find a different angle.
Sign language
Game design
Creative Writing
Ceramics/Drawing/other Art
CPR/First Aid
Financial Management
Economics
Debate
Botany
Astronomy (may not be possible depending on the amount of light pollution where you live — will also probably require some night time “lab” classes).
Nutrition
Photography
The Wolf