The best, portable, rechargeable music lamp is made by Lampcraft. Our Community band checked out about everything available and ended up buying 60 of them. A few of us piggybacked an order for personal ones onto the main order (quantity discount). Check them out at:
http://www.lampcraft.com/ . I can't speak for the LED "Giglight", we have the fluorescent tube "Concertlight II". The built-in battery is good for upwards of 3-4 hours and that's the small battery.
They aren't cheap... but you get what you pay for!