http://www.buzzxp.com
http://www.noolmusic.com/fat/buzzfat.shtml
http://buzzmusic.wipe-records.org
http://buzzwiki.wipe-records.org
http://www.xlutop.com/buzz
http://ohm.objectis.net/instruments/
Just making george's post more obvious.
Too many things to quote here, but if you're doubting the quality of buzz machines, you'd be in for a surprise if you actually tried buzz. Either way, nice plug from Oldfield. Doesn't beat Kraftwerk/Steinberg though.