The circuit above is able to flash a 1.7V or 2.0V LED using 1.5V DC input battery. It is a charge pump design.
1.5V powered LED flasher – [Link]
In this article learn about the LM3914 Dot/Bar Display Driver IC. This IC reads an analog voltage and converts this value to a display of 10 LEDs in bar or dot format. This is a nice component to experiment with. On the video above see a demonstration of LM3914 as a voltmeter with a range of 0~5VDC.
The LM3914 Dot/Bar Display Driver – [Link]
Instructables user duesentrieb shows us how to build a multicolor flashlight including infrared and ultraviolet. He used a cheap torch found on ebay and some inexpensive parts.
How to build a multicolor flashlight - [Link]
PICtris project is a tetris game using dot led displays controlled by a PIC microcontroller. PIC18LF4520 is drawing 2D graphics on LED display and four buttons control and rotate the blocks. Find schematics and source code on the link below.
PICtris: Tetris on a PIC MCU - [Link]
In this article learn how to drive LEDs using linear circuits, including transistor constant current circuits.
Linear LED power supplies - [Link]
This should be one the the most hard to ready binary clocks as it uses different color to display hour, minutes and seconds in binary form. Check description on the link below to find out how to read it.
CoMBi Clock: RGB binary clock - [Link]
Simon Inns @ Waiting of Friday builds a cool VU meter using RGB leds. RGB leds are controlled by 3 TLC5940 LED driver chips and PIC18F2550 microcontroller. Source code and schematic is available on the link below. [via]
This project creates a RGB LED VU Meter which is controlled via USB by a Windows 7 or Vista host machine. The demonstration board consists of a 5V regulator (switching), a PIC18F2550 with the required USB components, 3xTLC5940 16 channel serial LED drivers with PWM and 16 high intensity RGB LEDs.
RGB LED VU Meter using TLC5940 LED Driver Chips – [Link]