The ADS1115 provides 16-bit precision at 860 samples/second over I2C and is perfect for microcontrollers without an analog-to-digital converter or when you want a higher-precision ADC. The chip can be configured as 4 single-ended input channels, or two differential channels.
The ADS1115 16-Bit ADC includes a programmable gain amplifier, up to x16, to help boost up smaller single/differential signals to the full range. It can run from 2V to 5V power/logic, can measure a large range of signals and it's super easy to use. It is a great general purpose 16 bit converter.
The chip's fairly small so it comes on a breakout board with ferrites to keep the AVDD and AGND quiet. Interfacing is done via I2C. The address can be changed to one of four options (see the datasheet table 5) so you can have up to 4 ADS1115's connected on a single 2-wire I2C bus for 16 single ended inputs.
Example code for both the Raspberry Pi (Adafruit Pi Python library) and Arduino (ADS1X15 Arduino library repository) can be found in the resources tab. Simply connect GND to ground, VDD to your logic power supply, and SCL/SDA to your microcontroller's I2C port and run the example code to start reading data.