At I Heart Switch, women talk about using electronic engineering to improve their lives. A recent project of theirs was about purses. Almost all purse carrying in the US is done by women, as a replacement for pockets that women's clothing often doesn't have and men's clothes almost always does. A common problem with purses is that they are dark inside, forcing the user to fumble around until she feels the tool she was looking for. This is even worse in unlit places like raves, movie theaters, and bars, where overhead illumination is insufficient to see even the top layer of the purse's contents.
So I Heart Switch's solution was an internally lit purse that activated a small light when the purse was open, and turning this light off when the purse was closed. A magnet determines the open/closed state of the purse, and a 9V battery provides the power. For aesthetic reasons, the battery, electronics, and back of the light can be sewn into fabric strips, which would then be sewn to the sides of the purse. The fabric strips conceal the electronics, which shouldn't be removed anyway.
The creator of this ingenious invention, Ms. Lewis, made a short video about its production.