Outdoor camera signal indoors without drilling?

Good luck...

I guess you could run the wire through a window, then seal the crack with duct tape.

....or get one of the kids to hold it out the window

There are wireless cameras.

However, you still need a power source, but maybe you have that already.

You can purchase wireless cameras that use encryption over the wireless. Also, don't worry about signal quality. I had a small spy camera in my car (damn neighbor backed into my car TWICE and denied it, but I got them the third time!) about 150-200 ft away and got perfect color signal. The rated range is about 300', and the camera was only about 1" X 1.5" + 9V battery or AC adapter. Unencrypted though, but no one around my neighborhood is that smart : )