The Devantech SRF08 is the advanced model of Ultrasonic distance rangers available, with excellent width-of-field detection, I2C interface, and light-intensity sensor!
The Devantech SRF08 is a dual-element high-performance ultrasonic distance ranger. Consider it a souped-up version of the SRF05! It's a great complimentary sensor to any of the Sharp-based IR distance sensors (like the DIRRS+, I2C-It, or AIRRS) in that it's sensitive to a much wider field of view, whereas the Sharp units are excellent at picking off small items.
Like the I2C-It IR ranging sensor, the SRF08 also uses the I2C interface, so you can chain up to 16 sensors in a single string. And the SRF08 has configurable addresses so you can hook more than one at a time in the same chain.
The SRF08 has configurable maximum range, which can be useful if you want more rapid sensor firing. By limiting how long the sensor waits for the ping back, you have it reset and retrigger faster than having it wait for the full 65mS cycle time.