Honeycomb
I like this one, although the zig-zag nature of the led strip runs make a lot of pre-built effects somewhat lackluster on it. If you take that into account, however, you can make it do some neat stuff.
art
Circle Frame
My usual method of invention is keeping enough things up in the air at once, that the right combination of things to solve my problem randomly fall into my lap at any given time.
Oil Lamps
I was experimenting with different liquid densities, colors, and lights to make something not entirely unlike a lava lamp.
Tube Light
I wasn't sure what to expect when I switched it on, so I was pleased when light sprang forth from the strips and illuminated the entire tube. Unfortunately, once the sun came up the next day, I realized this would only ever be an accent lamp.
Arch
It looked really cool, and was great at getting shadows out of my work space, but it was tippy and a bit more fragile than it looked, so away it went.