If you need a free delay effect plugin that simply does its job, then T. Rex Delay Mini by Max Project is for you.
T. Rex Delay Mini is distinguished by a vintage analogue GUI design, with three big rotary knobs: Delay, Feed and Level.
Currently it is available for Windows as VST 2.4 effect plugin, 32-bit only, but can be run on 64bit systems using jBridge.
T. Rex Delay Mini can be downloaded for free (instant download) at Max Project website. The download size is 3.9MB.