One of the newest additions to the Electro-Harmonix Nano range is the Soul Preacher Compressor/Sustainer pedal. And very nice it is too.
Though its diminutive in size this unit is packed with warm, user-friendly musical compression. When used on fast attacks or percussive sounds such as drums, it adds a healthy dose of aggression along with a wide variety of tones.
We found it quite surprising just how many various treatments and vibes two rotary controls and a three-way switch could produce.
Using the pedal as an insert on bass and vocal sounds proved less useful however. This is a guitar pedal first and foremost.
With its high-impedance inputs and signal-to-noise ratio, it's really more suited for in-line use with the instrument it was designed for.
Major plusses for build quality too - it's built like a miniature tank - and has heaps of character and control for its teeny tiny price tag. I challenge you to find a better alternative