Occasionally the light in your Jeep isn't all that great for reading maps or other objects. Sometimes you just need a little more light. Here's my cheap solution.
Hat clip lights. There's a ton of them on the market from 5 dollars and up. Here's a few examples. Some will be better then others.
They clip right on your visor, almost completely unnoticeable and stay on great with the top off. All you have to do is turn them on flip down the visor and its pointed right at you. A side benefit is the fact that if you need it quickly, you can grab it right off your visor and use it outside the vehicle. Comes in handy.