I took 8 of these modules, about a meter long each, and hung them from the ceiling in a semi random pattern, mapped them to a 2D plane in software, and used MIDI data from Ableton live to trigger light patterns that would be played across the LED array. Decent party trick.
It unfortunately was mostly destroyed when someone fiddled with the variable voltage supply it was hooked up to in an attempt to turn it off post-party. Word to the wise: if there are knobs on equipment at a party (mixer, lighting, etc), people will inevitably fiddle with them. Design for this.
The tree could be wrapped with the LED strips then the position of the LEDs was obtained using a camera (as they pulse out an ID).
I then created a little Flask app, that ran on the same Raspberry Pi which controlled the LED strips, which let people paint the tree via a website.
Controlled by a Raspberry Pi, great for an office or a shared space. I ringed the door with LEDs.
One I've loved the most is ambient lighting. I ringed the ceiling of one of my rooms with these and I can fade them in and out to a warm or cool white. It is great for hanging out with friends since there's this warm glow coming from all directions. Also great for reading. My next step is to create areas that I can light up sections above chairs and sofas.
It's also fun and easy to attach these to bikes. You can then just ziptie your arduino under the seat or somewhere like that and then light up your frame.
If you have a GPS module, you can build a compass or something that always points to the same spot.
You could also give your sofa and chairs underglow.
Lately, I was also thinking it could be fun to try 3d-printing some little spherical diffusers for individual 5050 LEDs and arranging individual ones of those in a larger area like a window.