I picked up these LED
submersible light balls a few months ago since I had a coupon and had nothing else to get (compulsive buyer, right here). They are meant for wedding floral arrangements and such, but they work for aqaurium use too. I'm not 100% comfortable about putting them inside of the tank though...
They have clips on the back, so I clipped them on to the back edge of my glass top on my 10g betta coccina tank. I think they look pretty good. Probably not enough to grow the plants, but they get plenty of natural light.
Anyway, just thought I would share! All the major craft stores carry them, in case anyone was interested.