This is my arduino-based waveform generator using a 8-bit resistor ladder DAC. It runs with a sampling rate of 65536 Hz and can create any (whole-number) frequency from 1 Hz to 30ish KHz in sine-wave, sawtooth, triangle and different ratios of square wave.
My generator produces an amplified signal and also a unamplified, high-quality signal. There is a LCD built in that shows the current frequency, and also a speaker. The LCD is actually a hacked cheap pocket calculator, for which i found out how to press CE, +, = and 1 with the arduino to make the LCD show a specific number. Yes I know that this is a stupid hack :). The generator runs from a 9V battery. Two videos are shown below; one for the hacked calculator display and one for the generator itself.