I've been wanting to light up my rum collection (which is in a wooden bookcase) for a while now. After looking around at different cheap options, I found the IKEA diode puck lights, and went with those.
Very thin, great light and do an amazing job lighting up the bookcase. You get 4 pucks per pack, and each comes with sticker backing and really long cord. I used black tape to hide the white cords. Each of the 4 wires attaches to a central hub, which then plugs in. I placed 2 under each shelf, and because they are so thin, you can't see them when standing in front. Dead easy. I'm really happy with how it turned out, and looks great with all the bottles lit up at night. Would recommend them to anyone for a similar project.
Here's the link for the dioder at IKEA.