Valhalla DSP ValhallaFreqEcho MkI, a FREE delay effect for both Windows and Mac OS X that looks useful.
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"Bode-style frequency shifter + analog echo emulation = skull melting chaos. Perfect for dub, Dr. Who and all of your psychedelic needs. Sonic results range from subtle chorusing and double tracking to barberpole phasing and flanging to endless glissandos and runaway echos" ValhallaDSP