Bubble displays were intensively used in vintage electronics. Back then LEDs were small and inefficient so they were placed under bubble lenses to make it look bigger. Today we have different situation with multicolor bright large LED displays. But those old ones actually look pretty attractive and gives nice flavor to product.
Markus has build a simple alarm clock which features a four digit bubble display. Clock is run on MSP430 microcontroller that runs RTC inside. Clock is powered with single AAA battery what makes it really small. There is a speaker to ring an alarm which is augmented with LED flashing. So there is no way you could sleep any more.