Scorpion - yes, multiple paint jobs in various versions
Venom - at least three times
Doc Ock - at least twice, not counting the movies
Electro - once in a box set and more recently with an action feature
Green Goblin - too many times to count, including various artist versions plus the movie version
Hobgoblin - once very early on in SC line
Demogoblin - on the shelves now but it's just a repainted Hobgoblin from the early waves
Manwold - Nope
Lizard - multiple versions including one on the pegs in a repaint now
Vulture - only in the Sinister Six box set
Shocker - very recent release (last fall)
Carnage - once in a box set, once carded, slightly different paint
Kingpin - only in the face off two packs with Daredevil (white suit and variant black suit)
Hydro - hydroman is a craptasticular figure released in the same wave as Shocker
Morbius - very early SC release
Mysterio - early release but repaint is out in the  2007 line
Scarecrow - nope
Rhino - multiple versions including a repaint out now.  Ultimate, classic and other versions exist
Beetle - yeah, but a horrible figure
Sandman - yes he's out, earlier SC release, might be a repaint about, will be a movie version
Kraven - early release in SC line plus in Sinister Six box set, repaint out in 2007 line
Black Cat - only in the S6 box set; also an expensive Marvel Select version
Punisher - comic and Thomas Jane versions exist, also released in a box set, plus the face off two packs
Bullseye - marvel legends release (series 8?)

I'll add more detail but that's all I had time for now.