With 144 pixels per strip, this is easily the king stripxel of the techno-color jungle.
RGB LEDs are cool. The small surface-mount ones are even cooler. But WOW, full flexible strips of RGB LEDS are neat! But these aren't just a strip of LEDs that all change color at the same time - you can individually control each LED!
These Solarbotics stripxels come with 144 LEDs per meter! Each RGB LED connects to the well-documented WS2812B RGB controller IC, so you simply power up the string with 5V, and use the FastLed Arduino library to send the data to each pixel.
You can snip these strings apart in 1 LED increments at the points marked on the strip, so if you really want to stretch them out, you can snip and patch-wire them different lengths or segments (assuming you are running sufficient 5V power to each segment).
Oh, and did we mention they are waterproof? They are IP67 rated which means they can handle going under water (but try not to place the ends in as well, as they are much less waterproof). Officially, the IP67 rating is descibed as "protected against the effect of immersion between 15cm and 1m". They also come with an adhesive backing that will allow you to affix them to almost anything!
Arduino Library: http://fastled.io/
These are sold by the meter!